A small-sized opening and closing device which relatively connects a first member and a second member with each other to open and close, and is composed of a shaft, a cam member attached to said shaft, a slider cam attached slidably to said shaft facing to said cam member; a compression spring wound around said shaft to push said slider cam toward said cam member side, and wherein said cam member and said cam slider each having two kinds of cam portions located on an axial core side and an outer circumferential side.