The present invention provides a manual on-off valve with good operability. A weir-type manual on-off valve (1) includes a valve body (4) having a weir (43) formed between a first flow path (4a) and asecond flow path (4b); a valve seat (43a) formed on the weir; a diaphragm valve core (5) abutted against or separate from the valve seat; a pressing spring (9) that presses the diaphragm valve core against the valve seat when the valve is closed; and a housing (3) with the built-in pressing spring (9); a handle (2) fitted to the housing (3); and a rod that is connected to the diaphragm valve core(5), penetrates between the housing (3) and the handle (2) and is held in an axially movable manner. In the valve, the rod has a first rod (6) and a second rod (8) arranged in the axial direction, and an external thread portion (6a) is formed on the outer peripheral surface of the first rod (6). In the inner peripheral surface of a through hole (31d) through which the first rod passes of the housing (3), an internal thread portion (31a) in screw-thread fitting with the external thread portion (6a) is formed.