To simplify the structure of a damper valve of a hydraulic power steering to facilitate its manufacture and assembly and to reduce manufacturing cost.

A partition plate member 32 for partitioning the inside of a valve casing in two valve chambers has a plurality of through-holes 35 formed at equal spaces in a circumferential direction. A first valve spring plate 36 for opening/closing the alternate through-holes 35a out of the through-holes 35 is fastened to one wall surface of the partition plate member 32 facing the first valve chamber 33 on the oil path selector valve side out of two valve chambers, and a second valve spring plate 37 for opening/closing the other alternate through-holes 35b out of the through-holes 35 is fastened to the other wall surface of the partition plate member 32 facing the second valve chamber 34 on the power cylinder side out of two valve chambers. The outer diameter of a first flat washer 38 holding down the first valve spring plate 36 is made larger than that of a second flat washer 39 holding down the second valve spring plate 37, and the spring strength of the first valve spring plate 36 is made larger than that of the second valve spring plate 37.