A hinge assembly includes a mounting sleeve defining a pivoting hole, a fastening seat, an elastic member, and a right side cover. The pivoting hole is enclosed by an interior peripheral wall. The interior peripheral wall defines a stopping slot. The fastening seat defines a fastening hole. The elastic member is received in the mounting sleeve. The right side cover includes a pole. The pole includes a first resisting bar and a second resisting bar. The pole is received in the pivoting hole and the fastening hole. The first resisting bar is slidably embedded in the stopping slot. The elastic member compresses the first resisting bar to abut against the fastening seat. When the first resisting bar slides out of the fastening hole and abuts against the fastening seat, the second resisting bar is slidably embedded in the stopping slot.