The aim of this paper is to clarify characteristics of expressions of gratitude in daily conversation (mainly in Japanese), by contrastive analysis in Japanese, modern Greek, English, Portuguese, French and Chinese. In this analysis I have pointed out the basic structure of "arigato (gozaimasu)", which is not so obvious to foreign students and even to many Japanese. This seems to be one of the characteristics of Japanese expressions. This contrastive analysis has clarified the similar structure in modern Greek, English, French and Chinese but not in Japanese, that is the way to express directly the feeling of gratitude in consideration of structure of expression. The basic structures of most common expressions of gratitude are not very clear in Japanese, Portuguese and French.