a hydraulic pressure regulating valve for regulating a pressure in an automatic transmission of a motor vehicle , comprising a magnetic part which includes an electrically controllable coil , a coil core and a movable armature , a valve flange which is anchored on the magnetic part and has pressure medium guiding passages , a piston controlling a pressure in a passage connected to a consumer , the piston being loaded with the armature and controlling pressure medium connections between the passages , a diaphragm element which seals the valve flange relative to the magnetic part , a return passage , the diaphragm element having at least one pressure chamber which is hydraulically connected with the return passage , and a throttling device formed so that the pressure chamber is connected with the return passage through the throttling device .