To provide an EGR valve which can make compatible the securement of a sealing force of a seal member and the improvement of the durability thereof.

An EGR valve 10 includes a valve housing 12 in which a gas passage 14 for passing EGR gas is formed, a valve seat 18 provided in the gas passage 14, a valve shaft 26 having a valve element 30 for opening and closing the gas passage 14 when seated and separated on/from the valve seat 18, an actuator 13 for moving the valve shaft 26 in the axial direction, and a seal member 60 which is provided on the valve housing 12 and elastically seals a space between the valve housing 12 and the valve shaft 26. A shaft part of the different shaft diameter is formed in the valve shaft 26 so that the clamping margin of the seal member 60 is changed according to the opening/closing of the valve element 30.