A Fourier transform type spectrophotometer capable of stably controlling a speed of a moving mirror comprises a movable unit to which a moving mirror is fixed, outside-force-applying means configured to apply external force larger than movement resistance of the movable unit to the movable unit, a driving source configured to apply positive or negative driving force along the moving direction of the movable unit to the movable unit, a speed measurement unit configured to measure the speed of the movable unit, and a driving force control unit configured to control the driving force of the driving source so that the movable unit is moved in a predetermined manner based on the, wherein a rate of fluctuation of the driving force is suppressed by operating in a state in which the driving force of the driving source is high due to the external force to thereby stabilize the control.