EVAPORATED FUEL TREATMENT DEVICE

An evaporated fuel processing device may include: a canister that communicates with a fuel tank though a tank passage, communicates with an intake passage of an engine through a purge passage, and communicates with open air through an open air passage; a control valve that switches between a closed state of closing the purge passage and an open state of opening the same; a pump that changes a pressure in a communicating space in a case where the control valve is in the closed state, the communicating space defined by the fuel tank, the tank passage, the canister, the open air passage, and the purge passage on a side closer to the canister relative to the control valve; a pressure detector disposed in the communicating space; and a determining unit that determines the evaporated fuel processing device is not operating normally by using a pressure detection result by the pressure detector in a state where the control valve is in the closed state and the pressure in the communicating space is changed by the pump.