In a valve seat structure of a fluid control valve comprising a valve element, a body formed with an inlet port and an outlet port, and a valve seat member provided in the body, the fluid control valve being configured to bring the valve element into or out of contact with the valve seat member to control the flow of a fluid, the valve seat member is formed in a ring shape and includes a valve seat portion with which the valve element will come into our out of contact. Assuming that a thickness of the valve seat portion in a radial direction of the valve seat member is a first thickness t1 (0