A resin composition formed by blending 10 to 25 weight parts of the epoxy modified polystyrene resin (B) to 100 weight parts of the liquid crystal polyester and/or the liquid crystal polyester amide (A) and by melt-kneading the two materials, wherein the resin composition having a melt viscosity of 60 to 4000 Pa·s at a shear rate of 1000/second at a temperature which is 20° C. higher than the melting point and having a melt tension of 20 mN or more at a take-over speed of 15 m/minute, is melt within a temperature range of a melting point to the melting point +40° C., a parison P is formed by extruding it with an extrusion speed equal to or higher than 0.3 kg/minute and lower than 5 kg/minute, a pair of moldings placed so as to sandwich the parison P are closed at a predetermined mold closing pressure, and air is blown into the parison P.