A hydraulic pressure control valve comprises a valve body having a slide bore of a circular cross-section and an inlet port and an outlet port opened into an inner surface of the slide bore at axially spaced apart points, and a valve spool slidably received in the valve body for axially sliding movement and defining, by cooperation with the valve body, a variable orifice for controlling the degree of communication between the inlet and outlet ports. In the hydraulic pressure control valve, a smaller diameter portion defining an annular oil passage between an inner surface of the slide bore is provided on the valve spool coaxially with the slide bore to define the variable orifice, and has an outside diameter set constant over axially entire length. This facilitates the dimensional control of the variable orifice, so that the variation in property of the variable orifice for every hydraulic pressure control valve may be easily suppressed.