An apparatus for forming a pipe frame for use in a vehicle seat is disclosed in which spring clamps are welded to a rectilinear pipe material of a predetermined length at the predetermined positions thereof, the pipe material is then bent into a required configuration, one of two ends of the pipe material is then compressed to form such a smaller diameter portion as to be insertable into the inside diameter portion of the other end, and the compressed smaller diameter portion of the one end is forcibly inserted into the other end so that the inserted portion of the pipe material is welded.