EVAPORATED FUEL TREATMENT APPARATUS

An evaporated fuel treatment apparatus includes an abnormality determination unit that determines an abnormality of a purge passage. The abnormality determination unit changes an operating cycle of a purge control valve to a cycle longer than an initial set value while maintaining a duty ratio of the purge control valve set according to an operating state of an internal combustion engine, and determines an abnormality of the purge passage based on a first variation range and a second variation range calculated from a detection value detected by an airflow meter before and after the change of the operating cycle.