A fuel cell with a wet state control device, comprising: a priority control unit (B101, B103, B201, B203) for controlling either one of a pressure and a flow rate of cathode gas when a wet state of a membrane of a fuel cell is adjusted; a water temperature control unit (B102, B202) for controlling a temperature of cooling water when the wet state of the membrane is not completely adjustable by a control of the priority control unit (B101, B103, B201, B203); and a complementary control unit (B103, B101, B203, B201) for controlling the other of the pressure and the flow rate of the cathode gas to complement a response delay of the water temperature control unit (B102, B202); wherein: in the case of drying the membrane by decreasing the wet state of the membrane, the priority control unit (B101, B103, B201, B203) decreases the pressure of the cathode gas; the water temperature control unit (B102, B202) increases the temperature of the cooling water when the wet state of the membrane is not completely adjustable by the control of the priority control unit (B101, B103, B201, B203); and the complementary control unit (B103, B101, B203, B201) controls the flow rate of the cathode gas to complement the response delay of the water temperature control unit (B102, B202). a priority control unit (B101, B103, B201, B203) for controlling either one of a pressure and a flow rate of cathode gas when a wet state of a membrane of a fuel cell is adjusted; a water temperature control unit (B102, B202) for controlling a temperature of cooling water when the wet state of the membrane is not completely adjustable by a control of the priority control unit (B101, B103, B201, B203); and a complementary control unit (B103, B101, B203, B201) for controlling the other of the pressure and the flow rate of the cathode gas to complement a response delay of the water temperature control unit (B102, B202); wherein: in the case of drying the membrane by decreasing the wet state of the membrane, the priority control unit (B101, B103, B201, B203) decreases the pressure of the cathode gas; the water temperature control unit (B102, B202) increases the temperature of the cooling water when the wet state of the membrane is not completely adjustable by the control of the priority control unit (B101, B103, B201, B203); and the complementary control unit (B103, B101, B203, B201) controls the flow rate of the cathode gas to complement the response delay of the water temperature control unit (B102, B202). in the case of drying the membrane by decreasing the wet state of the membrane, the priority control unit (B101, B103, B201, B203) decreases the pressure of the cathode gas; the water temperature control unit (B102, B202) increases the temperature of the cooling water when the wet state of the membrane is not completely adjustable by the control of the priority control unit (B101, B103, B201, B203); and the complementary control unit (B103, B101, B203, B201) controls the flow rate of the cathode gas to complement the response delay of the water temperature control unit (B102, B202). the priority control unit (B101, B103, B201, B203) decreases the pressure of the cathode gas; the water temperature control unit (B102, B202) increases the temperature of the cooling water when the wet state of the membrane is not completely adjustable by the control of the priority control unit (B101, B103, B201, B203); and the complementary control unit (B103, B101, B203, B201) controls the flow rate of the cathode gas to complement the response delay of the water temperature control unit (B102, B202).