PURPOSE: To obtain the homogeneous FRTP moldings having high strength by supplying both the cut material of a glass fiber bundle covered with thermoplastic resin and thermoplastic resin having melt viscosity higher than the said resin into a molding machine and imparting a required shape in pressurization and heating.

CONSTITUTION: A long-sized glass fiber bundle is continuously passed in the melt of thermoplastic resin low in melt viscosity to coat the surface with this thermoplastic resin. Both the cut material of this glass fiber bundle and thermoplastic resin having melt viscosity higher than the said resin are supplied to a molding machine. A required shape is imparted in pressurization and heating. Thereupon thermo-plastic resin having high melt viscosity is comparatively low in conformableness with glass fiber and hardly penetrated into the inside of the glass fiber bundle but is good in conformableness with thermoplastic resin having low melt viscosity. Therefore coating to the glass fiber bundle previously treated by thermoplastic resin having low melt viscosity is made good. Thermoplastic resin having high melt viscosity is homogeneously and easily mixed.