To provide an opening and closing device mainly used for various electronic devices, which is capable of various operations by an excellent feeling.

Slopes 27A and 24A are provided to an outer circumference of a movable cam 27 and an inner circumference of a fixed case 24. After the movable cam 27 elastically touches a flat part 2B of the fixed cam 2, a biasing force in the opening direction is relaxed by the friction between the slopes 27A and 24A upon an opening operation by bringing the slopes 27A and 24A of the movable cam 27 and the fixed case 24 into elastical contact with each other, thereby preventing the impact on a movable casing 22. Also, when the movable cam 27 is held at an angle within a predetermined range where the movable cam 27 elastically touches the flat part 2B of the fixed cam 2, the movable casing 22 can be surely held at the desired angle by the friction between the slopes 27A and 24A, thereby obtaining the opening and closing device capable of various operations by the excellent feeling.