An operation of a change valve is changeable between a valve closing state, in which the change valve is closed to close connection between a pump passage and a canister passage and to open connection between an atmosphere passage and the canister passage, and a valve opening state, in which the change valve is opened to open the connection between the pump passage and the canister passage and to close the connection between the atmosphere passage and the canister passage. An ECU determines that the change valve is abnormal when a value, which is obtained by subtracting a second reference pressure measured in an (n−1)th execution of a fuel vapor leakage sensing process from a first reference pressure measured in an nth execution of the fuel vapor leakage sensing process, is equal to or larger than a predetermined threshold value.