To provide a method and an apparatus for manufacturing a large-sized and long welded brush, which is difficult to be welded by an ultrasonic technique, by a high frequency welding, and to provide a high frequency welded brush single body.

By the high frequency technique, the periphery in the vertical or cross sectional direction and side face direction or the like of bundled brush bristles (thermoplastic resin) is pressed by a jig serving also as an electrode and a high frequency generated by a high frequency welding machine is supplied to the electrode. Then, the thermoplastic resin itself generates heat and melting occurs among the brush bristles. When oscillation is stopped and the thermoplastic resin is cooled and fixed, the light-weight welded brush without bristle fall-out, which is excellent in terms of recycling as well, is perfected.