In the modern world, primarily in developed countries, education has become the main factor of intergenerational social mobility. Sociologists judge the degree of openness or rigidity of the social structure by whether the inÀuence of “birth circumstances” on access to education increases or, conversely, softens. Although higher education has become widespread in Japan by now, this does not mean that the degree of social inequality in this area has decreased. Structuring children’s chances of access to higher education along the lines dividing society into diɣerent social strata begins here at the stage of schooling – ¿rst, in lower secondary school, and then in upper secondary school. The inequality of chances that forms at the stage of school education aɣects the choice of university rank and directions of specialization by children and their parents, employment opportunities in the future, determining, in fact, the entire life path of a person. Based on the works of famous Japanese sociologists and the data of Japanese statistics, the author shows that the Japanese education system plays a dual role. On the one hand, it provides a chance to break away from one’s social roots and move up the social ladder to an increasing number of young people. On the other hand, it preserves and reproduces social inequality. According to calculations by Japanese sociologists, indicators of relative social mobility, reÀecting the ratio of chances to access higher education for people from diɣerent backgrounds, were remarkably stable throughout the post-war period. On the one hand, this does not con¿rm the widely accepted thesis about the growing inequality in education in the last two or three decades. On the other hand, it allows us to assert that both before and now Japanese society is a kakusa shakai, or a gap society. However, the increase of the share of second-generation university degree holders in the structure of Japanese university graduates suggests that the scale of the inÀuence of the factor of social inequality in education will gradually decrease.