A hydraulic pressure control device for a transmission, which operates a hydraulic apparatus by hydraulic pressure generated by an pump driven during operation of a driving force source, for which automatic stop control is performed, accumulates the hydraulic pressure in a pressure accumulator, and supplies the hydraulic pressure accumulated in the pressure accumulator to the hydraulic apparatus when the driving force source is automatically stopped is provided. The automatic stop control includes control to stop the driving force source when the vehicle speed is equal to or higher than a prescribed vehicle speed; and the hydraulic pressure control device performs a control to control an accumulated oil amount in the pressure accumulator and the automatic stop control in a manner to increase the accumulated oil amount of the pressure accumulator when the driving force source is automatically stopped.