A mouth switch is provided for a multifunction operation microscope (1). Signals to be outputted to the operation microscope can be switched from one provided when only a long main lever (21) is held with a mouth (lips, teeth, and the like) to another provided when a sub-lever (25) is held together with the main lever. Even if the number of functions to control increases, the mouth switch can cope with them. The mouth switch can change signals through the simple operation of holding the levers with a mouth, and therefore, possibility of an operation error can be reduced. As a changeover switch (22) is OFF, the mouth switch provides four kinds of signals including focus-up, focus-down, zoom-in, and zoom-out signals, and as for ON state, other four kinds of signals relating to X(+) direction, X(-) direction, Y(+) direction, and Y(-) direction for shifting field of view are provided.
