To easily and accurately adjust operational characteristic of a light shielding blade.

The driving characteristic adjustment mechanism for a driving mechanism 100 is provided. The driving mechanism 100 includes a rotor 101 composed of a permanent magnet, and a yoke having leg parts arranged to be opposed to the peripheral surface of the rotor 101, and performs opening/closing operation of the light shielding blade coupled to a driving pin 106 provided to the rotor 101 by moving the driving pin 106 back and forth as the rotor 101 turns, wherein the yoke 102 is provided to turn with the center of rotation of the rotor 101 as center, and a projection 112 making energizing force for turning the yoke 102 in a predetermined direction act on the yoke 102, and a screw 114 and screw hole 116 energizing the yoke 102 in an opposite direction to the predetermined direction and turning the yoke 102 against the energizing force by the projection 112 are provided.