A hinge mechanism includes a shaft (1), a cam (2), a housing (3), an arresting member (6), a cam follower (4), and an elastic member (5). The housing has an open housing end (30), and an opposite partially open housing end (31) including a transverse wall (35). The cam, the cam follower, the elastic member and the arresting member surround the shaft in turn. The cam follower and the elastic member are received in the housing. The cam is partly received in the housing. The transverse wall of the partially open housing end of the housing prevents the cam from sliding further into the housing. The arresting member is disposed adjacent to the open housing end allowing the arresting member sliding into the housing. The cam is rotatable relative to the shaft and non-rotatable relative to the housing, and the cam follower is non-rotatable relative to the shaft.