OPENING AND CLOSING MECHANISM

An opening/closing mechanism includes: opening/closing member including rotating portion on rotation axis; and cam member to face the rotating portion of the opening/closing member on the rotation axis and to apply a load to rotation of the rotating portion. One of the cam member and the rotating portion includes: at least one first-cam-projection provided on first circumference having the rotation axis as center; and at least one second-cam-projection provided on second circumference having the rotation axis as center, with the second circumference being larger in radius than the first circumference. The other member includes sliding face over which the first and second cam projections slide. The opening/closing mechanism has: first-angle-range in which the first-cam-projection slides over the sliding face and the second-cam-projection does not slide over the sliding face; and second-angle-range in which the second-cam-projection slides over the sliding face and the first-cam-projection does not slide over the sliding face.