PURPOSE: To obtain a molded item which is excellent in mechanical and electrical properties and has a high thermal stability by molding a polyimide formed by linking arom. dianhydride units to diamine units with fluorinated linking groups under specified temp. and pressure conditions.

CONSTITUTION: A polyimide polymer having repeating units represented by formula I (A is a tetravalent arom. group contg. a benzene, a naphthalene, or a polyphenyl nucleus, etc.; B is a divalent arom. group provided at least either A or B contains a tetra- or a divalent arom. group represented by formula II or III; and n is 100-200) is molded at 300°C or higher under a pressure of about 176 kg/cm2 or higher to give a molded item. This polymer is produced by dispersing about equimolar amts. of an arom. diamine and an arom. dianhydride in an org. solvent in a concn. of about 8-12 wt.% and subjecting the diamine and the diahydride in the dispersion to polycondensation by heating under almost isothermal conditions.