An oil pressure regulating valve of rotary type comprising a valve body and a valve spool is constructed inside a housing having a cylindrical shape. An oil supply port for supplying pressure oil fed from an oil pressure generation source is formed at a position having an offset toward one side relative to the center axis of the housing. A communicating hole in a deep inside of the oil supply port in communication with the inside of the housing is an elongate hole which is long in the direction of offset. As a result, in a hydraulic power steering apparatus, flow sound is reduced effectively that is generated when the pressure oil fed from the oil pressure generation source is supplied to the oil pressure regulating valve inside the housing. Accordingly, quiet operation is achieved.