An apparatus which may be used to convert conventional length putters to long putters while also providing an adjustment feature over a large range to accommodate virtually all golfers who wish to use long putters which have the precise length suited to their individual needs. The preferred embodiment comprises a first extension shaft which is a hollow tube inserted into the upper end of the conventional putter shaft after an end portion of the grip has been removed to reveal the upper end. The first extension shaft terminates in a threaded portion. A threaded nut is then secured to the threaded portion. A second extension shaft, slightly smaller in diameter than the first extension shaft, is then inserted into the first extension shaft to achieve the desired putter length including an extension grip affixed to the upper end of the second extension shaft. Another threaded nut is then placed on the remaining portion of the threaded portion and in surrounded engagement with the second extension shaft to set the overall length by tightening set screws.