A valve mechanism includes: a cylindrical body; a plurality of valve bodies; and a drive valve. The drive valve includes a shaft portion having a flow path penetrating in the axial direction, and a first step portion extending from an outer peripheral surface of the shaft portion to a radial outside of the shaft portion. The shaft portion has a protrusion portion protruding further toward the cylindrical body side than the first step portion and a base portion extending to a side opposite to the protrusion portion with respect to the first step portion. A gap between the valve bodies is changed by elastically deforming an inner peripheral portion of the valve body, which comes into contact with the drive valve moved in a direction approaching the valve body, in a direction approaching the cylindrical body with respect to an outer peripheral portion of the valve body.