VAPORIZED FUEL TREATMENT DEVICE AND LEARNING METHOD OF VALVE OPENING START POSITION OF SEALING VALVE IN VAPORIZED FUEL TREATMENT DEVICE

A vaporized fuel treatment device includes a sealing valve disposed in a vapor passage between a fuel tank and a canister and including a valve element that moves in an axial direction with respect to a valve seat, a cut-off valve that cuts off a communication between the canister and an atmosphere, a pump that reduces an internal pressure of the canister, a vapor passage diagnostic module that decreases an internal pressure of the fuel tank by the pump via the canister so as to diagnose whether leakage occurs in the vapor passage in a state where the communication between the canister and the atmosphere is cut off and the sealing valve is opened, and a learning module that executes a learning of a valve opening start position of the sealing valve based on a change in the internal pressure of the fuel tank when changing an axial distance between the valve element and the valve seat when the internal pressure of the fuel tank is equal to or smaller than a predetermined value after a diagnosis of leakage in the vapor passage.