A joined type valve seat has a coating layer of thickness of 10~m or less. The layer has a coefficient of thermal expansion of an intermediate value between the valve seat material and the cylinder head material. The surfaces of the valve seat contacting with the cylinder head are coated. Where the valve seat is made of Fe-base sintered alloy, the layer will have a coefficient of thermal expansion of 15 x 10 -6 - 25 x 10 -6 (1/K). Where the valve seat is made of Cu-base alloy, the layer will have a coefficient of thermal expansion of 18 x 10 -6 - 27 x 10 -6 (1/K). Where the seat is made of ceramics the layer will have a coefficient of thermal expansion of 10 x 10 -6 - 20 x 10 -6 (1/K). The coating will be a pure metal or alloy layer (e.g. Cu, Ag, Ni). The seat is joined to the cylinder head by welding. The cylinder head is preferably aluminium alloy.
