A mirror controller of an optical switch comprises a signal generator (10, 82, 83) for passing the optical signal on the same light path as the one for optical communication using the optical switch, and an image analyzer (15, 16, 81) detecting the optical signal as the light scattered by at least one of tilt mirrors (111, 123) and an output collimator array (14). The image analyzer detects the position of the light beam image as a control position (121, 141, 85) based on the scattered light, and controls the tilt mirrors in such a manner that the detected control position coincides with the predetermined desired target position (122, 142, 84, 86) on at least one of the tilt mirrors and the output collimator array. The mirror controller can realize the connection test of the optical signal between input and output with high accuracy and reliability.