To improve flexibility of a shaft.

Concerning at least a part of a shaft part S of a badminton racket 1, a cross section vertical to its axis is nearly diamond-shaped and the longer diagonal of the diamond shape is arranged in parallel with the racket face surface 10 of a frame part F. In this case, at the time of the forehand swing of a right-handed player and the back swing of a left-handed player, the curving rigidity of the part S is lowered to improve flexibility of the part S, thereby the head speed of the racket is increased.