Fast, strong and steady racket swing can be made, without having a special skill.Providing a band which is made of one or more materials of fiber, resin, rubber, leather, metal, and other elastic material, and/or providing a fingerhold for a thumb and a fingerhold for an index finger, or a fingerhold for a thumb, which are made of one or more materials of fiber, resin, rubber, leather, metal, and other elastic material, and by pushing down or pushing up the fingerholds, the racket grip is turned to the side of fingerhold or to the other side of fingerhold, and inward or outward rotation operations of the racket grip continue, making the best use of a series of racket swing which started from the take-back.