Valve

A valve comprising a valve body that has a primary flow path and a secondary flow path formed in an interior and includes a cylinder and a case housing a pressure displacement means, a valve port being formed in a partition wall disposed between the primary flow path and the secondary flow path, a valve mechanism portion penetrating through an interior of the cylinder, the valve mechanism portion including a piston that is housed reciprocally slidably inside the cylinder, a valve stem that penetrates through the piston, a valve main element through a center of which penetrates a lower end portion of the valve stem that has penetrated through the valve port, and the pressure displacement means to which is fixed an upper end portion of the valve stem, and the valve comprising a secondary side communication flow path that puts a pressure sensing chamber formed, below the pressure displacement means, inside the case in communication with the secondary flow path wherein the valve stem has a downwardly open hollow portion of cylindrical shape, a supply hole that puts the hollow portion and the pressure sensing chamber in communication is formed at an upper end side of the valve stem, and the secondary side communication flow path is formed with the supply hole and the hollow portion.