PURPOSE: To obtain a product consolidated in situ and having low porosity from a yarn impregnated with a thermoplastic resin by guiding yarns having a plurality of lengths along a spiral path under a specific condition with a guide crossing a mandrel in axial direction.

CONSTITUTION: A feeding arm 14 movable in a direction approaching to or separating from a rotating mandrel 16 is attached to a traversing carriage 12. The feeding arm 14 is provided with an infrared heater 18, a heated guide 20 and a flame heater 22. Yarns 24 having different lengths and impregnated with a thermoplastic resin are preheated with the heater 18 while being drawn out under a specific tension, the temperature of the thermoplastic resin is increased with the guide 20 heated to a temperature between the melting temperature of the thermoplastic resin or thereabout and the decomposition temperature of the resin and the temperature is maintained with the flame of the heater 22 to ensure the molten contacting face at the winding position 28.