First, clinical characteristics of pervasive developmental disorder (PDD) were summarized, with a focus on impairment in social interaction, obsessive traits, and a liability to fall into a panic. Differences between subtypes of PDD as well as comorbidity were also explained. Then the conventional idea of criminal liability and how psychiatric factors are related to the idea were reviewed, which indicates that the core impairments of PDD were not regarded as factors that affect the judgment on the criminal liability. Detailed analyses on the behaviors of criminals with PDD, however, seem to provide evidence that they were not completely criminally liable. Possible relationships between the criminal liability and the neural background of PDD were discussed.