PROBLEM TO BE SOLVED: To directly and firmly bond resin to rubber without using an adhesive.SOLUTION: A composite body formed by directly bonding a resin member to a vulcanized rubber member is obtained by combining: the vulcanized rubber member vulcanized with a radical-generating agent (e.g., an organic peroxide or the like); and the resin member comprising a thermoplastic resin having at least 2 atoms, on average, selected from H and S atom per molecule, each atom having an orbital interaction energy coefficient S not smaller than 0.006 represented by the following formula (1): S=(C)/|E-E|+(C)/|E-E|, where Eis the orbital energy (eV) of a radical, Cis a molecular-orbital coefficient of a highest occupied molecular orbit (HOMO) of an n-th H atom constituting a basic unit of the resin, Eis the orbital energy (eV) of the HOMO, Cis a molecular-orbital coefficient of a lowest unoccupied molecular orbital (LUMO) of the n-th H or S atom, Eis the orbital energy (eV) of the LUMO, and all the values are calculated by a semiempirical molecular orbital method MOPACPM3.