PURPOSE: To obtain an adhesive for thermoplastic resin member to which a high frequency adhesive method is applicable by allowing a conductive compound to be contained in an inorganic solvent that softens the thermoplastic resin member.

CONSTITUTION: An inorganic solvent used herein is of the type that it can evenly soften the joined surfaces and thus generates a combination between both the surfaces to be joined with only slight pressure. For a conductive compound, a low molecular weight compound is used that has no reaction with an inorganic solvent used here and has conductivity and, in particular, e.g. water, lower alcohol and the like having an OH group is used. A mixture of the inorganic solvent and conductive compound is applied on at least one joined surface of two thermoplastic member, and thereafter they are brought into press contact with each other and, when high frequency voltage is applied on the adhesive, the solvent can be dried in a short time.