In an endoscope apparatus, a suction button unit (29) (switching valve unit) includes a valve cylinder (50), a piston rod (51), a cap device (52) and seal packing (53). Holes are formed in a piston chamber (54) of the valve cylinder, including a discharge port hole (56), a suction port hole (57) and an exhaust port hole (58). The piston chamber includes a piston slide surface (54a) and a sliding sealing surface (54b). A passage in the piston rod connects the exhaust port hole with the suction port hole in case the piston rod is in a halfway position, and connects the suction port hole with the discharge port hole in case the piston rod is in a position of full depression. The seal packing, in the halfway position, closes the discharge port hole, and in the position of full depression, causes the discharge port hole to open. Thus, operability and washability of the suction button unit can be high.
