An optical switch device (1) of such a type that the COUPLED state of light guides is switched by moving a light reflective member capable of securely preventing a movable body with the light reflective member from being displaced and allowing a reduction in thickness, comprising a pressing member (41) switching the movable body (2) with a prism mirror (10) mounted thereon between a clamped state and an unclamped state, a twisted spring (60) energizing the pressing member in a clamping direction, and a magnetic drive circuit (45) for clamping driving the pressing member (41) in the unclamped state against the torsion spring (60). The magnetic drive circuit (45) for clamping further comprises a clamp coil (72) on the fixed member (13) side and clamp magnets (70, 71) on the pressing member (41) side. The clamp magnets (70, 71) are disposed so as to hold the clamp coil (72) from the inside and outside of the opening thereof with the different poles thereof opposed to each other.