Mapped data of line pressure set to any of high pressure/low pressure regions on the basis of an engine load are stored in a storage section. A determining section 103 determines, on the basis of temperature of the hydraulic oil detected by an ATF temperature sensor 18, whether the mapped data the low pressure region is shifted in an enlarged direction. A state determining section 104 determines whether a throttle valve opening degree TH of the vehicle is totally closed or whether the line pressure is currently set to low line pressure. When the low pressure region is shifted in the enlarged direction and the throttle valve opening degree TH is totally closed or the line pressure is currently set to the low line pressure, a region changing section enlarges the low pressure region of the mapped data stored in the storage section.