To provide a flow control valve capable of reducing an influence of a change in the viscosity of a control fluid.

The flow control valve includes a sliding shaft 30 and a sliding cylindrical face 21a fitted mutually to slide in the axial directions, and a moving mechanism 40 for moving the sliding shaft. The fluid is controlled between a V-shaped tapered groove 33 formed on a surface of the sliding shaft 30 and the sliding cylindrical face 21a. The V-shaped tapered grooves 33 is shaped to be gradually decreased or increased according to a prescribed function. The sliding shaft 30 of the moving mechanism 40 and the sliding cylindrical face 21a are formed of materials having different thermal expansion coefficients, and the change between flow passages by the temperature change and a flow rate change amount by the change of viscous resistance are canceled with each other.