Abstract: A flexible pipe joint system has three swivel joints on the both sides and in the central portion thereof, and two arm pipes connecting the swivel joints. The swivel joints have a stepped cylinder body, an elbow and a cap nut. The stepped cylinder body has a larger diameter portion and a smaller diameter portion. The elbow has a pipe connection portion to which a nipple provided with a flange on its outer end and a nut member on its outer periphery. A short cylindrical adapter is provided at one end of the arm pipe connected to the pipe connection portion of the elbow and to one end of the arm pipe connected to the smaller diameter portion of the cylinder body. The adapter and the nut member, respectively, have an outer diameter smaller than the inner diameter of the gasket and an inner diameter of an end portion of the cap nut.