Clutch pressure is reduced when a vehicle is stopped with an engine (1) in an idling state. Once a turbine rotation speed increases to a predetermined rotation speed, the clutch pressure is increased to an initial pressure. After the initial pressure is reached, the clutch pressure is controlled to a target hydraulic pressure at which a slip amount reaches a target slip amount. Once the clutch pressure converges, a correction value for an initial pressure is set in order to make the slip amount approach the target slip amount. The set correction value is stored in a memory region corresponding to a transmission oil temperature at the point when the correction value is set. The initial pressure is corrected by the correction value stored in the memory region that corresponds to the transmission oil temperature when the turbine rotation speed has increased to the predetermined rotation speed.