A roughened rubber bonding surface having a predetermined roughness of a rubber member and a roughened resin bonding surface having a predetermined roughness of a resin member made of a thermoplastic resin are connected to constitute a bonding interface, and ultrasonic vibrations are applied to the bonding interface from the rubber member side. Only the resin member is fused by friction heat generated in the bonding interface so as to force fused resin into the rubber member, and the fused resin that has been so forced into the rubber member is solidified therein, whereby both the rubber member and the resin member are mechanically bonded by virtue of an anchoring effect produced by the two members which are entangled together.