To provide a constant flow rate valve with a low cost which can install it the place with a small fluid pressure.

When a water pressure becomes high, a second flow route 14 and third route 15 are crushed by the elastic deformation and crush of a projection 13. Thereby, these flow route sectional areas become small. This flow route sectional area becomes small as the pressure of a city water becomes big. Therefore, the supply amount of the city water is regulated so as to keep a fixed amount. Thus, in the fixed flow rate valve installed on the place with a small fluid supply pressure, the projection 13 easy to elastically deform is provided and the water amount is held in a fixed flow rate by pressing to the holding part 9 by the water pressure and deforming and crushing the second flow route 14. Thereby, a constant flow rate valve with a low cost which can install to the place with a small fluid supply pressure is provided.