A braking structure for a turning body includes an engagement device rotatably engaging a movable-side portion of a rotation damper with a base at a rotation center of the movable-side portion; a first fixing device fixing the movable-side portion relative to the turning body; and a second fixing device fixing a stationary-side portion of the rotation damper relative to the base. The engagement device includes an axis protrusion provided on one side of either the movable-side portion or the base, and a receiving portion provided on the other side of either the movable-side portion or the base, and receiving the axis protrusion from a direction perpendicular to a rotation axis of the rotation. Also, an inserting path for the axis protrusion continuing to the receiving portion is adapted to expand in the direction perpendicular to the rotation axis by an elastic deformation when the inserting path receives the axis protrusion.