A golf putter used for golf game is disclosed, wherein the putter head is mounted with an observation unit equipped with at least one or more from a prism, a convex mirror, a concave mirror and a lens capable of allowing a player to directly observe a target direction, a strike point of a golf ball and an alignment state between the ball and the target with the naked eye from above a putter face, and the observation unit is mounted with an aiming unit configured with linear and circular shapes to allow the target direction and the putter face to be squared and to allow a player to precisely strike the sweet spot, such that the target direction and a rear surface of the ball can be observed in person with the naked eye to accurize the putting in terms of distance and straightness, and heads-up can be avoided.