Abstract: A golf practice sighting device which is adapted to be demountably attached to the shaft of a putter for aiding a golfer in accurately aligning the putter with a golf ball and a target. The device includes a viewer containing a 45.degree. mirror. When the viewer is properly positioned the 45.degree. mirror reflects an image of the area directly in front of the putter which can be seen by the golfer when in his normal stance above the golf ball and looking down toward the golf ball. The viewer is clamped to the shaft of the club by an assembly made up of two brackets pivotally connected to each other. The viewer further includes a pair of slidably mounted gauge pins for squaring the device relative to the face of the head of the putter.