To provide a slide switch device smoothly operated, having superior durability, in which the operating direction of an operating member of the slide switch and the movement direction of a knob of a switch element performing electric switching cross each other at right angle, and an optical instrument having the same.

In the slide switch device, a cam engaging with the knob is installed at a coupling member 9 which operates integrally with the operating member 1, and the both ends of the cam are formed in circular arc shape. The middle part of the slide switch device is made to contact the circular arc at both ends, and connected by a straight line of which angle between the operating direction of the operating member 1 and itself is 45° or less, and an optical instrument having this is provided.