A pipe joint and a method of joining pipes using the pipe joint prevent loss of a sleeve, enhance workability in the pipe joining operation, and ensure sealing performance. The pipe joint may be utilized in a refrigerant device, a heat pump hot water supply device, a closing valve and a water supply piping. The method for connecting piping may be used in an in-the filed piping method. The pipe joint includes a joint body, a fastening member such as a nut, and a sleeve. The sleeve is integrated with the fastening member or the joint body before the fastening member is attached to the joint body. When the fastening member is attached to the joint body, the sleeve is cut off and separated from the fastening member or joint body. When the nut is fully attached, the sleeve bites into the pipe, and the pipe is joined to the joint body.