くはない is just a construction to mean "not necessarily/ it's not that....,"(as in "it's not that it is bad... (but...)". For i-adjectives it is formed by changing the last い into く and then adding はない(です). The は is pronounced as "wa" in this case.

Not a native speaker but as far as I can see you could break it further down like this:

わるく: badly (adverb form of わるい)

は: topic particle attached to わるく

ない: is not, does not exist

です: politeness marker

So a very literal translation would be "as for badly, 'it' is not". Or a little more freely: "Bad is not the way in which [it] exists".

Note that it's essentially the same as わるくない without the は. The topic particle puts more stress on the "bad": "It isn't bad [but...]"

i think HA(wa) mean "IS" its like when i was studing english, i asked: why i need to put "IS" every time.in Russia: IT (is a) MEAT - ЭТО МЯСО.

I'm basing my comment on other answers and my intuition, so take this with a grain of salt, but..

わるく is the adverb form of わるい, which changes it from "bad" to "badly". the は particle indicates topic, and ない is "not". so i think the best way to translate this that conveys the nuance would be, "as for 'badly', that is not the way in which this exists". idiomatically, it seems that this means, "it's not necessarily bad".

Friendly not to everyone: don't downvote honest questions. Someone else might have the same question and need it answered.

When you negate an "-i adjective", the final "i" turns to a "ku" and you add "nai". That's why わるい (warui) becomes わるくない (waruku nai) (or in this case the more complicated わるくはない "waruku wa nai").

No.

I understand what they're doing with the translation, it's not perfect but translating Japanese nuance into English never is. When you say "It's not bad", to me there's usually a positive connotation. When you say "it's not necessarily bad" it implies that it's not necessarily good either. I can't think of a time when "not necessarily bad" would have a positive meaning, but maybe I'm just thinking too small.

It emphasizes the "bad", and thus deemphasizes negation. It ends up meaning something like "It's not bad[, but...]" or "It's not necessarily bad".

Link is broken for me, FYI

Kirai - when you dislike something. Warui - when something is bad.

I don't think that quite hits the nuance. Ever2662 posted a helpful link and started a good discussion about the meaning.

To come back to your original question (as the one about contrastive vs topic は seems already fairly exaustively discussed below): I’m afraid you’re getting a few things mixed up here (understandably – は is rather difficult to wrap your head around at first if you don’t speak a topic-prominent language already).

は does not mark the subject but the topic – the thing that is placed at the focus of the sentence and then commented on. The only way you can emulate this in English is with the rather contrived formula: “As for x,…” Oftentimes the subject also happens to be the topic because situations where we want to tell somebody what some person (whom we both know) did. But that doesn’t have to be the case. If it’s not, then the non-topic subject is marked with が instead (that is, if it’s not omitted because it can be understood from context). For example:

• この本は読みましたか？ (“As for this book, did you read it?” <- the object “this book” is the topic).
• あのマンションには幽霊があると聞きました。 (“As for in that apartment building, I heard there are ghosts [there].” <-- the place adverb “in that apartment building” is the topic)

If you want some guidelines on what should be made the topic, here are some rules of thumb I found:

• The topic is pretty much always “old information” – something that the speaker expects the listener to know about. It may be something that came up in the conversation before, a proper name that they expect the listener to recognize, or maybe a general category such as “dogs” or ”teachers” in general.
• The topic is never ever a question word such as “who, what, where”. Also in the answer to a question containing such a word, the part that answers the question word is never the topic either. So for example, if you want to ask who ate your cake, “who” couldn’t be the topic, the cake would be: わたしのケーキはだれがたべましたか？ And similarly, the culprit who answers “I ate the cake” couldn’t make “I” the subject because it answers the question “who”. So they would say: わたしがたべました。 The reason for this is actually the same one as the point above: If you’re asking a question, the question word – and the answer – represent new information that you don’t know yet. So it cannot be the topic. (I’m guessing it was examples like this one that gave you the idea of は having a de-emphasising effect? If so, I suggest forgetting that idea because it’s only a side-effect of its real purpose, and only in this kind of sentences.)

Now there is also a second application of は which some people like to keep separate as “contrastive は”, others understand it as a special application of the topicalising function. In any case, here は is used to contrast two (or more) things against each other. For example:

• 犬は好きんだけど、猫は大嫌いです。 (“I like dogs, but I hate cats.” <-- dogs and cats are contrasted with は)
• この映画はもう見たけど、あの映画はぜったい見ない、こわいから。 (“This film I have already watched, but that film I am absolutely not going to watch, it’s [too] scary.” <-- the two films are put in contrast. Note also how they are in fact emphasised here even though they are marked with は, because of the contrast.)

And as IsolaCiao pointed out, this is also the function it has in our example sentence above, only the second part of the contrast is left implicit. This is where the implicit “but” comes from – if it’s not bad, it must be something else: “It’s not bad [but…]”

You can view this as a second application of は if it helps you. I personally don’t view it as fundamentally different from the topicaliser は because it essentially still does the same thing: It takes two known things and puts them in focus, so you can make a comment about them. It’s just that those two things happen to contrast with each other in the greater context. But if it helps you to treat it as a separate function, then by all means, do that :)

は isn't a topic marker here, it is the contrastive wa.

From Stack Exchange:

This is a prime example of the contrastive は. What and where is the contrast in the sentence 「今の仕事は悪くはないです。」, then? It is left unsaid.

When a Japanese-speaker hears or reads a sentence like that using は, he will instinctively "know" that a few words were implied but not said. Those words would be something like 「でも、（特とくに）良よくもないです。」. Particles 「は」 and 「も」 are often used in a pair like that.

「このピザはまずくないです。」 means the pizza is at least average in taste. It may well be a little better than average.

「このピザはまずくはないです。」 means the pizza is average at best.

Umm, no, AbunPang's explanation above is 100% correct. わるく is the topic. ないです is related to the topic but is never the topic. は does not really de-emphasize the subject, but it only serves to bring up the topic (as to emphasize that the topic has some kind of relationship). In this case it is the comparison that it is not BAD but is something else.

わるくない it is not bad わるくはない it is not necessarily bad

悪くない means it is not bad, while 悪くはない means that it is not necessarily bad. You wont get wierd looks unless you use it incorrectly

If you check out some of the discussion above, you'll see that わるくない would just be "it's not bad", but to convey the "not necessarily" part you need は.

That is, for this translation

It is actually wa, but the robo reader confuses it sometimes