This study investigates the speech act of thanksgiving comparing the speakers of Korean in South and North Korea. An underlying hypothesis is that there may be differences in pragmatic competence of the subjects in the two groups despite the presumed absence of significant differences in their organizational competence to organize discourse with a shared grammar. In order to identify differences in perception and linguistic realization of gratitude, a questionnaire survey has been conducted and its results are statistically analyzed using a chi-square test. The quantificational analysis consists of the perception, degree, target, and the frequency of gratitude expression, and the results show statistically meaningful differences in all these areas. Among significant generalizations is that North Koreans, who hold relatively negative views toward thanksgiving as compared to South Koreans, turn out to express gratitude at a lower frequency. This basic difference leads to mutual misunderstanding: North Koreans view that South Koreans, who profusely give thanks even for insignificant things, do not know decency and are frivolous in words rather than in action, whereas, conversely, South Koreans view North Koreans, who would be expected to express gratitude but fail to do so, are impudent and disrespectful. It is believed that this comparative analysis of thanksgiving speech act revealing differences in perception and expression can help the two groups of Korean speakers better understand each other and become more receptive and tolerant of different verbal behavior. It is hoped that more research in depth and width on diverse speech acts is conducted to help the two groups to overcome potential sources of miscommunications ensuing from differences in language use in specific contexts and, in more general terms, different communication patterns.