A gap 11 between a flange 4A of a bail support member 4 and the inner circumferential surface of a sleeve member 7 functions as an orifice for restricting an oil flow downstream of a seat hole (6B). The movement of the ball support member 4 is stabilized, pressure is generated in a chamber 9 downstream of a seat hole 6B, and the override characteristics of the relief valve 1 are improved.