To provide a string which has an excellent repulsive property to a ball, makes it possible to obtain a soft ball fitting feel and is small in tension loss.

This string is made of a synthetic resin having core yarn and side yarn around the same and is specified in the dynamic hardness expressed by the equation: S(N)=0.125 f2 to 6,000 to 12,000 N. In the equation, (f) is the vibration frequency (Hz) generated in the string when a weight of 35.7 in mass is attached to the center of the string of 356 mm fixed at both ends and is allowed to make simple harmonic motion under the tension of 267 N.