The present article aimed to review literature of Willingness to Communicate (WTC) in second language learning and its application to the research of Japanese language education. This study examined the following questions: (1) what is WTC in second language? (2) why is WTC study needed for Japanese language education? (3) how has WTC been investigated and what were the results of the previous researches? (4) what are the important problems to solve? This review suggests that WTC has a positive effect on oral proficiency in second languages, and that further research should be undertaken to find out the effective ways of improving WTC.