PURPOSE: To easily produce at low cost a thermoplastic liquid-crystal-forming resin made highly resistant to melting by heating a thermoplastic liquid-crystal- forming resin molding in the presence of finely divided carbon or compd. thereof up to a temp. of at least the glass transition point of the molding.

CONSTITUTION: A thermoplastic liquid-crystal-forming resin molding is heated in the presence of finely divided carbon and/or finely divided compd. thereof up to a temp. of at least the glass transition point of the molding. The resin to be used is a polymer melt-moldable and capable of forming liquid crystal which has mesogen groups in the main chain thereof. This type of resins include polyarylates and arom. polyester-amides, especially pref. examples of which include those having structural units of formula I (wherein X and Y are each H, halogen or at most 4C alkyl), formula II, formula III or the like.