MALFUNCTION DIAGNOSIS DEVICE FOR LEAKAGE DIAGNOSIS DEVICE

A leakage diagnosis device for an evaporative fuel treatment device includes a first vent valve, a second vent valve, and a pump. The first vent valve is configured to block a first atmospheric passage, which is a main passage of an atmospheric passage and connects a canister with an atmospheric opening. The second vent valve is configured to block a second atmospheric passage, which is a bypass passage of the first atmospheric passage and connects the canister with the atmospheric opening. The pump is provided on a side of the atmospheric opening relative to the second vent valve in the second atmospheric passage, and is configured to pressurize or depressurize the second atmospheric passage. A malfunction diagnosis device performs a malfunction diagnosis based on an output value of a pressure sensor, a current value of the pump, or an output value of an air-fuel ratio sensor.