An endoscope valve for controlling connection states of a plurality of conduits formed in an endoscope includes: a piston portion； and an attachment member. The piston portion includes a seal portion. A surface of the attachment member facing the seal portion includes a first inner peripheral surface which is axially symmetrical to a central axis of the attachment member and has a diameter smaller than a diameter of an outer periphery of the seal portion, a second inner peripheral surface which is axially symmetrical to the central axis of the attachment member and has a diameter equal to or larger than the diameter of the outer periphery of the seal portion, and a connection surface which is axially symmetrical to the central axis of the attachment member and connects the first inner peripheral surface and the second inner peripheral surface to each other.
