To provide a sliding switch device in which its casing is made smaller.

A click spring 31 which is made movable along a side part of a casing at a time of operation of a sliding knob 61 is provided with: a engagement part 36 which is engaged with a switching lever 44 of a switch 43 and which makes a switching by moving along the side part of the casing; a projected part 32 which makes a click feeling on moving along the part of the casing; a positioning rib; and a leaf spring 34 which makes an elastic deformation, provided with the engagement part 36, the projected part 32, and the positioning rib. The positioning rib is arranged between the engagement part 36 and the projected part 32 in a moving direction of the click spring 31. The switch 43 is arranged in a position overlapping in a thickness direction with the engagement part 36 so as to make smaller a dimension L in a thickness direction and to make smaller the sliding switch device.