A hinge assembly (100) includes a sleeve (20), a main shaft (10), a follower (30) and an elastic member (40). The sleeve integrally forms an engaging portion (26). The main shaft passes through the sleeve. The follower has a cam surface (322), and is slidably placed around the main shaft and is received in the sleeve. The cam surface engages with the engaging portion. The elastic member provides an elastic force to bias the cam surface against the engaging portion.