Hi Ryoko. "I don't mind" is more polite, and indicates that you are still interested in the subject of conversation. "I don't care" could be interpreted in some situations as a lack of interest. Hope that helps!

We usually say "I don't mind" when something potentially negative happens, but it doesn't make us upset. For example: - I forgot to return the book I borrowed from you! I'm sorry! - Oh, I don't mind! Bring it back whenever you like. - It's raining today, but I don't mind, I have an umbrella. "I don't care" has a broader meaning than "I don't mind." It means "this isn't important to me". I disagree with Mario a little - I think "I don't care" isn't always rude. You can usually use it in the same situations as "I don't mind", but it's more informal. So with a friend, I could say "Oh, I don't care! Return it whenever you like" and it would be okay. "It's raining, but I don't care", is also fine. BUT, "I don't care" can definitely be very rude! For example: - I'm feeling so sick today! - I don't care. or - It's my birthday! - I don't care. Obviously, that's rude. X)

Thank you, Ollie, for your explanation! It helped me a lot. :)

Both can say that you don't have a preference about something and can be used in response to someone asking about your opinion. (1) "Where do you want to eat?" "I don't care, as long as the food's good." (Note: Here, 'where' is used to represent a restaurant or the like) = "Where do you prefer to eat? I don't have a preference." (2) Can we eat at McDonald's?" "I don't mind." = "Is it alright with you if we eat at McDonald's?" "It's alright with me. " So... 'I don't care' can be used broadly in informal conversation. 'I don't mind', however, can be a more polite way of giving your consent or simply saying that you're not against a particular idea. I realize this is a bit late in reply, but hope it helps! :)

Both can say that you don't have a preference about something and can be used in response to someone asking about your opinion. First: Where do you want to eat? I don't care, as long as the food's good. (Note: Here, 'where' is used to represent a restaurant or the like) --- is very similar to... --- Where do you prefer to eat? I don't have a preference. Second: Can we eat at McDonald's? I don't mind. --- is very similar to... --- Is it alright with you if we eat at McDonald's? It's alright with me. "I don't care" can be used broadly in informal conversation. "I don't mind", however, can be a more polite way of giving your consent or simply saying that you're not against a particular idea. I realize this is a bit late in reply, but hope it helps! :)