A manual valve of a hydraulic pressure control system for an automatic transmission includes: a valve body including a first exhaust passage that includes an exhausting hole and an intake hole that are communicated with a drive range port in a neutral range, such that a transmission fluid, which is supplied from the drive range port when the vehicle is shifted from drive to neutral, is exhausted; and a hydraulic pressure exhaust control unit that is disposed in the exhaust hole so as to control an exhaust amount according to an exhaust pressure.