Driving techniques are provided for achieving a sufficiently low-speed drive and smooth change in the drive speed. Voltage is applied to an electromechanical element by repeating an output cycle in which one voltage value out of a first voltage value is output during a first period, a second voltage value lower than the first voltage value is output during a second period, a third voltage value lower than the second voltage value is output during a third period, and finally the second voltage value is output during a fourth period. Further, a mechanism for changing the lengths of the respective periods is provided to allow for a sufficiently low-speed drive and smooth change in the drive speed.