PURPOSE: To restrain impact vibrations and expand sweet spots in hitting a ball by securing a composite material consisting of a specified vibration restraining material and buffer material fixedly to a gut of a racket through the buffer material.

CONSTITUTION: A composite material 4 having tow combined layers of a specified vibration restraining material 5 and buffer material 6 is secured fixedly to a gut 1 through the buffer material 6. For the vibration restraining material 5 is preferably used a resin setting composition mainly containing an epoxy resin having fluidity at room temperature through 100°C, a polyamide resin and an inorganic filler selected from graphite, ferrite and mica. The resin setting composition has the high degree of freedom of working to provide easily a laminated composition with the buffer material and display a soft and extremely excellent vibration attenuating effect. Also, for the buffer material 6 are used inorganic or organic elastomer, rubbery elastomer, polymer gel or the like having 5.0kg/cm2 or less of compression hardness in 25% compression specified by JIS K676 and functions for improving and aiding the attenuation of impact vibrations of the vibration restraining material.