Abstract: A golf club shaft includes a first strain gauge attached to a first side of the shaft facing the striking direction, a second strain gauge attached to a second side of the shaft facing the address direction at right-angles to the striking direction, and a third strain gauge which is capable of measuring the twist of the shaft. Detection signals from the strain gauges are used to classify a shaft into four types according to the swing type of a golfer in accordance with at least torque or kick point.

Abstract: The present invention provides a putter club 10 which minimizes the reaction from the golf ball 5 during putting, effectively and appropriately transmits the putting force to the golf ball 5, and provides an effective sense of putting distance.The present invention is characterized by the location of the center of rotation P (center of instantaneous impact or shock) of the putter club 10 during putting at a position on the grip 4 (especially locating it on the grip area 6), by this arrangement minimizing the reaction from the putter club to the hands, and by the location of the center of rotation P of the shaft 2 during putting on the grip 4, making it easy to control the entire putter club.