If it is you are welcome as in "Il n'y a pas de quoi" Then we say "전만에요" Cheon man eyo !

You are right, Shàîmae. It's like saying Sure/It's nothing/No problem. I say 천만에요 when people say thank you for a big help I gave to them but people just don't use it. I've never heard other people say 천만에요 when I say thanks.

Many Korean textbooks teach the expression “천만에요 [cheon-ma-ne-yo]” as the proper response for 고맙습니다 [go-map-seum-ni-da] and 감사합니다 [gam-sa-ham-ni-da], both of which means “Thank you”, but 천만에요 is not really used very often in everyday modern Korean. Instead, what you most commonly hear is 아니에요 [a-ni-e-yo].