This study aims to investigate (1) whether Japan-born children with migrant parents, defined as second-generation immigrant children here, are behind the majority whose parents are both Japanese regarding high school educational attainment and (2) who are more disadvantaged among second-generation immigrant children. With nationwide longitudinal survey data tracing those who were born in 2001, this study found the following results; (1) the high school rank of children from mixed parentage (Japan-immigrant parents) is lower than the majority, and social and economic backgrounds possibly account for this difference, (2) among second-generation immigrant children, those with East Asian parents (Korean and Chinese) educationally achieve the same level as the majority while those with parents from other countries are left behind, and (3) children from immigrant mother and Japanese father are more disadvantaged in terms of the high school rank, but this difference can be accounted for by children’s backgrounds. These results indicate that Japan-born children from mixed parentage cannot benefit from having social ties to the Japanese majority. Furthermore, in more general sense, it is necessary to consider the intermarriage processes of parents to deepen the understanding of socioeconomic integration of their children in a host society.