A fluid control valve for controlling high-temperature fluid includes: a valve body including a valve chamber communicating with first and second flow passages, and a valve seat provided in the valve chamber; a metal diaphragm that contacts with and separates from the valve seat; a stem that moves the metal diaphragm up and down; and an actuator that drives the stem. The first flow passage includes a first orifice having a diameter set to 50% or less of a diameter of the second flow passage. Alternatively, the second flow passage includes a second orifice having a diameter set to 50% or less of the diameter of the second flow passage. The diameter of the second flow passage is calculated by converting a cylindrical flow passage area defined between the valve seat and the metal diaphragm when separated from the valve seat into a diameter of a circular flow passage.