The present invention provides an interferometer and the like, that is capable of ensuring the speed stability of the movable mirror while achieving the speed up of the reciprocal movement of the moving mirror and suppressing the increment of the maximum instantaneous thrust force required for the turning back as much as possible. The interferometer includes a moving mirror, a movement mechanism for reciprocating the moving mirror, a movement control part for controlling the movement mechanism and allowing the moving mirror to be reciprocated at a constant speed, and a measurement part for measuring a position of the moving mirror. The movement control part is adapted to receive target position data indicating a target position of the moving mirror, and control the movement mechanism to bring the measurement position of the moving mirror measured by the measurement part close to the target position indicated by the target position data.