PURPOSE: To provide a melting treatment device for a thermoplastic flexible material terminal to realize the shortening of treatment time, improvement of finished product quality, automation of treatment process, elimination of scale, reduction of treatment cost, improvement of working environment and prevention of fire.

CONSTITUTION: A device consists of a supporting member 3 for supporting a thermoplastic flexible material 1 to be able to vary its shape at least in its diameter direction is supported near its end 2 to be treated while being clamped and provided with a recessed section 4 in a manner of encircling the outer periphery of the end 2 to be treated, a vibrating member 5 for generating ultrasonic vibration to be disposed facing the recessed section 4 and to be able to melt the flexible material 1 and a press component 6 driving at least one of the support member 3 and a vibrating member 5 and pressing the vibrating member 5 to the end 2 to be treated.