PURPOSE: To easily strike a fastener without having a hole preliminarily formed by disposing plural lines of generally parallel reinforcing filaments at an axis direction on a matrix of a thermoplastic fastener member having a sharpened tip at one end.

CONSTITUTION: A thermoplastic fastener member 30 having a sharpened lower end 32 is comprised with a thermoplastic matrix 34 disposing plural lines of generally parallel reinforcing filaments 36. Then, sheet members 10, 12, which are formed of a thermoplastic matrix 14 disposing reinforcing fibers 16, 18, are piled up. Heating areas 20, 22 are heated to a half fusion flexible condition by a supersonic heating gun 26. The thermoplastic fastener member 30 is driven through the sheets to dispose penetrated. Expanding heads 44, 46 are formed at both ends by head forming metals 48, 50 to fasten the sheets. If one of the sheet members is a metal of other non-plastic material, a hole is formed in advance. The fastener is easily driven in this way, and is firmly connected thereto.