In a flow amount control valve, a rod is inserted through the interior of a housing, and first and second connecting members are connected coaxially to both ends of the rod. A first bellows and a second bellows, each having a bellows portion, are provided on the rod, for preventing leakage of fluid that is introduced into the interior of the housing. In addition, the first bellows and the second bellows are expanded and contracted by displacement of the rod along the axial direction, which is caused by driving an actuator, such that a valve element of the rod approaches and separates with respect to a valve seat, and a gap between the valve element and the valve seat changes so that a flow amount of the fluid is controlled.