A connector includes a plug and a socket that are connected and integrated to each other. The plug and socket each have an end to which a connection line may be respectively connected. The plug of the connector includes a plug body for connecting to the connection line and having a fitting recess on one end, a plug holder configured to be freely rotatably fitted over the plug body without slipping, and a stopper fitting configured to be freely rotatably fitted over the plug body and slidable in the shaft center direction. The socket of the connector includes a socket body for connecting to the connection line at one end and a socket holder. The socket body has an insertion portion configured so as to fit into the fitting recess of the plug body. The socket holder is configured to be freely rotatably fitted over the socket body without slipping.