A putter trainer device for detecting inaccuracies in a golf puffing stroke. The puffing trainer device of the present invention is releasably (2) attached to a shaft of a golf putter and comprises two guided ramps (19A, 19B) with each ramp having an active position and a neutral position. In one embodiment, a free rolling disc magnet (20A, 20B) is located upon each guided ramp and each free rolling disc magnet is biased towards the neutral position (23A, 23B) on its respective ramp. The movement of either free rolling magnet from the neutral position to the active position is detected by magnetic reed switches (25A, 25B) located adjacent each ramp. A speaker is activated when the magnetic reed switches detect that either free rolling magnet has moved from the neutral position to the active position.