A hinge assembly includes a first pivot unit including a shaft, a bracket, an engaging member, a locking member, and an elastic member. The shaft has a non-circular sleeve portion. The bracket is rotatably sleeved on the shaft. The engaging member has a sleeving hole with a shape substantially corresponding to a cross-section of the sleeve portion of the shaft. The locking member has a sleeving hole with a shape substantially corresponding to a cross-section of the sleeve portion of the shaft. The locking member is non-rotatably latched to the engaging member. The elastic member is sleeved on the shaft to resist the components on the shaft.