An opening and closing mechanism has an apparatus body 2 and an opening and closing member 3 that opens and closes by rotating with respect to the apparatus body 2, and also has a rod-like metal shaft member 8 that is mounted in the apparatus body 2. The opening and closing member 3 is rotatably supported about the metal shaft member 8 through insertion of the opening and closing member 3 between a guiding surface 7a1 having a circular arc surface shape provided in the apparatus body 2, and a surface 8a of the metal shaft member 8.