The moving mechanism has a first stationary-side gear part and a second stationary-side gear part provided on a support body side; a movable-side gear part and a pinion gear provided on a supported part of a movable body; and a guide device positioned so that the movable-side gear part engages with the first stationary-side gear part and the pinion gear engages with the second stationary-side gear part. The first stationary-side gear part is formed along an arc of a virtual circle, and has teeth oriented toward a center side of this virtual circle; the second stationary-side gear part is provided adjacent to this first stationary-side gear part on the center side of the aforementioned virtual circle, is formed along an arc of a separate virtual circle from this virtual circle, and has teeth oriented toward a center side of this separate virtual circle.