An electronic control unit (5) is configured to control a hydraulic pressures of engaging element and disengaging element in accordance with a preset target output shaft torque during a power-on downshift. The electronic control unit (5) is configured to delay a start of decrease in the hydraulic pressure of the disengaging element from a start of a torque phase while maintain the hydraulic pressure of the disengaging element at the start of the torque phase. The electronic control unit (5) is configured to start decreasing the hydraulic pressure of the disengaging element when the electronic control unit determines that overspeed of an input shaft (3a) is occurring during the torque phase and a predetermined condition is established.