EVAPORATED FUEL PROCESSING DEVICE

An evaporated fuel processing device includes a flow control valve that is used as a valve to be installed in a pathway connecting a canister and a fuel tank. The device includes an inner pressure sensor configured to detect a pressure in an interior space of the fuel tank as an inner pressure, a valve-opening start position determination means configured to calculate a second order differential value of the inner pressure after a valve opening operation of the flow control valve is started and to determine a valve opening position of the flow control valve as a valve-opening start position when the second order differential value is equal to or greater than a first predetermined value, and a learning means configured to store the valve-opening start position as a learned value that is used when a valve-opening control of the flow control valve is performed.