A piston assembly for a damper includes: a piston head; a piston rod having one end connected to the piston head, forming an inner space therein, and having another end at which an opening communicating with the inner space is formed; a wire having one end connected to an electric device mounted on the piston head and extending through the inner space of the piston rod; and a connector disposed at the other end of the piston rod and connected to another end of the wire. The connector includes a socket part rotatably disposed in the opening at the other end of the piston rod, and a plug part inserted into the socket through the opening of the other end of the piston rod. A self-alignment structure is provided in the socket part and the plug part and is configured to rotate the socket part such that the socket part is aligned at a predetermined orientation with respect to the plug part when the plug part is inserted into the socket part.