Patent ID: 7862448

Claim:
A golf shaft using prepreg in a partially hardened sheet form as a constituent part, obtained by impregnating a reinforced fiber material disposed substantially parallel with a thermal hardening resin material so as to bind thereof, wherein the prepreg is layered so as to form a tapered tube rod comprising a plurality of layers and having a diameter increasing from one end toward the other the tube rod is provided with a plurality of concave portions having a groove shape extending along an axis line direction of the tube rod spaced at a predetermined distance around a circumferential direction, each of said concave portions having a periphery being concave facing outwards from said portions, each of the concave portions being preliminarily formed on a circumferential wall surface of the plurally layered prepreg having a depth extending radially through at least one of the layers of the prepreg, and the golf shaft further includes a core member inserted into each of the concave portions along the axis direction and being in direct contact with an inside wall of the respective concave portion, as a strengthener in order to improve resilience thereof when the tube rod is deflected, and the golf shaft further comprises another prepreg wrapped around to cover the concave portions having the core members inserted therein from radially outward, so as to position the concave portions in an intermediate area along a thickness direction of the tube rod.