Flow rate control valve

Provided is a flow rate control valve that is capable of suppressing contamination of a controlled fluid by particles, maintaining a high level of cleanness of the controlled fluid, and rapidly controlling a minute flow. The flow rate control valve comprises a valve block (2), a diaphragm (1), and an actuator (3). Due to minute pressure received by the diaphragm (1) from the actuator (3), a fluid which has flowed through one flow path formed in an upstream part (2a) of the valve block (2) passes through a gap between an inner surface of the valve block (2) and an inner surface of the diaphragm (1), and is discharged from another flow path formed in a downstream part (2b) of the valve block (2). A peripheral part of the diaphragm (1) and an upper end surface of the valve block (2) are welded so as to be integral with each other. There is no level difference or gap between the inner peripheral surface of the diaphragm (1) and the inner peripheral surface of the valve block (2) at the welded part, and the inner