Therefore, only the cam 22 and the revolving-nosepiece switching lever 23 mounted above the driving gear 20 are described in detail below with reference to FIGS. 4 and 6 FIG. 6 is a plan view of the revolving nosepiece 10 of the microscope according to the first embodiment, which includes the cam 22 and the revolving-nosepiece switching lever 23 mounted above the driving gear 20.