A regulator performing fluid control includes an annular protruding portion having a valve seat on its leading end and an annular diameter-decreasing surface formed by decreasing an inner diameter of the annular protruding portion toward a valve hole. The regulator includes a valve element provided with a contact surface to be in contact with the valve seat and a columnar step portion provided on an inner peripheral side of the valve seat protruding from the contact surface toward the valve hole, the step portion having a diameter larger than an inner diameter of the valve hole and being coaxially formed with the valve hole. An annular ridge is formed by an outer peripheral surface of the step portion intersecting an end face of the step portion on the valve-hole side with the annular diameter-decreasing surface to constitute a passage narrowing portion.