An evaporated fuel processing device that includes a pump configured to supply purge gas, which includes evaporated fuel in a fuel tank, to an intake passage of an engine through a purge passage; a controller configured to control the pump; and a detecting unit configured to acquire a gas amount introduced to the intake passage while the pump is being driven in a stable state where an air amount introduced from open air to the intake passage is stable, and configured to detect, by using change in the acquired gas amount, a state where the purge gas is unable to be normally supplied from the purge passage to the intake passage.