A hinge assembly includes a shaft (12), a follower (16), a cam (18), and an urging means. The shaft has a screw portion (122) defined thereon. The follower has a first cam surface (164) formed on one end surface thereof. The cam has a second cam surface (184) formed on one end surface opposite to the follower. The cam has a screw hole (182) defined therethrough. The screw hole engages with the screw portion of the shaft. The urging means is configured for providing an urging force which moves the follower along the shaft and makes the first cam surface rotatably engage with the second cam surface of the cam.