Japan experienced rapid educational expansion after World War II, but social class differences in educational attainment still exist. To explain this persistent educational inequality, I ask whether the Breen and Goldthorpe (BG) rational action model could help explain the association between class origin and educational attainment. Using data from the Japanese High School Students and Mothers Survey conducted in 2012 and its follow-up waves (n = 1,070), I obtain the following results: (1) a student’s subjective probability of success and subjective benefits in terms of status maintenance are affected by his or her class origin, but that student’s subjective cost of education and motivation for status maintenance are not; (2) a student’s subjective cost, probability of success, and benefits affect educational attainment; (3) among those students with greater motivation for status maintenance, the effects of their subjective benefits are stronger; and (4) the subjective evaluations of educational options explain little of the effect of class origin on educational attainment. Although their explanatory power is limited, these findings mostly concur with the assumptions and predictions derived from the BG model of educational decision making, indicating the validity of the model for understanding the mechanisms underlying educational inequality in Japan.