A transition time is a time from a state where a movable portion has been rotationally displaced in the first direction and stopped to a state where driving portions apply the physical action forces to the movable portion to rotationally displace the movable portion in the second direction, which is different from the first direction, and the movable portion reaches a final displacement position. An elastic force value of the elastic supporting portion and the transition time have such a relationship that when the elastic force value of the elastic supporting portion is equal to a certain value, the transition time takes a local maximum value. The elastic force value of the elastic supporting portion is equal to or less than the certain value at which the transition time takes the local maximum value.