To smoothen a water flow and prevent the occurrence of pulsation even when a pressure difference between water and hot water is high by a method wherein a sheet metal fitting to close one end side of the cylindrical body of a thermostat forms a taper surface the diameter of which is decreased along the direction of a flow passage.

At a mixing valve for water combination faucet, water and hot water flowing in a housing 10 through a water inflow port 11 and a hot water inflow port 12 are mixed in a mixing chamber. A temperature-sensitive expansion contraction substance 15 retracts a protrusion 15a at a tip according to the sensing temperature of mixture water in the mixing chamber. By effecting fine adjustment of the position in an axial direction of a spool valve 16, automatic regulation to a set temperature is effected. In a thermostat 22, the shape of a sheet metal fitting 13 forms a taper surface 23 having diameter which is decreased along the direction of a flow passage. This constitution forms a flow passage for water formed by using the taper surface 23 and the inner peripheral surface of the spool valve 16 in such a manner to gradually spread. Thereby, even when a pressure difference between a feed pressure of water and a feed pressure of hot water is high, water smoothly flows and the feed pressure thereof exercises no adverse influence on the spool valve 16.