US Patent 9328826 Fluid control valve and mass flow controller

In order to, in a short period of time, reduce to zero a measured flow rate value measured after fully closing a fluid control valve, the fluid control valve having a configuration suitable to decrease the inside volume of the fluid control valve is configured together with a valve element member, and a valve seat block provided with: an in-valve flow path that is formed inside of the valve seat block; and a valve seat surface that is brought into contact with or separated from a seating surface of the valve element member is provided with a cutout that is formed in a part of a protruded rim so as to be communicatively connected to a downstream side flow path.