Here we investigate relations between the gripping force in golf driver swing and the golfer's skill. A grip force sensor, which does not influence to a golfer's hand, was newly developed by using a small flexible force detector made of conductive rubber. The point of greatest force fluctuation and the optimal site for measuring grip force were determined. Finally, features of the gripping force that the advanced or novice players exhibit were determined by experiments. Advanced players showed less gripping force fluctuation and weaker gripping force at the time of impact than novice players.