A clockwork mechanism includes: a supporting member; a movable member including an engagement hole and movably supported by the supporting member; a drive pin engaging the engagement hole, including a flange portion for preventing the drive pin from disengaging from the engagement hole, and revolving to move the movable member; a biasing member provided in the movable member to partially overlap the engagement hole; and an abutment member abutting the movable member to restrict the movement of the movable member. The flange portion overlaps or does not overlap the biasing member depending on a revolving position of the drive pin. When the movable member abuts the abutment member, the drive pin pushes the biasing member and the movable member is biased toward the abutment member by the biasing member. When the flange portion does not overlap the biasing member, the drive pin moves the movable member to push the biasing member, allowing the drive pin to disengage from the engagement hole.