Abstract Individuals with pervasive developmental disorder (PDD) are characterized by deficits in socialization. To date, moral judgment, which may have a considerable influence on socialization, has not been fully investigated in high-functioning PDD (HFPDD), particularly from a viewpoint of practical adjustment with peers. Human External Action and its internal Reasoning Type (HEART), a standardized test for evaluating moral judgment in school children developed in Japan, was used to compare various aspects of moral judgment between 23 students with HFPDD (6–14 years old) and 23 students with typical development matched for age, intelligence, and socioeconomic status. Students with HFPDD scored significantly lower on Internal Moral Reasoning than control students. As for the level of Internal Moral Reasoning, while both groups reached a conventional (third) level in almost all items, fewer students with HFPDD achieved an autonomous (fourth) level and more students with HFPDD remained at a heteronomous (second) level than did control students. In the HFPDD group there were significant positive correlations between some items of Internal Moral Reasoning and verbal ability-related items of Wechsler Intelligence Scale for Children-III. A comparatively lower score in students with HFPDD may relate to difficulty in socialization.