A golf swing training apparatus allows a user to learn a stable swing motion by acquiring a correct swing posture in performing a swing motion and to train turning motion of the user's shoulder and a rotating motion of the user's waist in a natural manner. The golf swing training apparatus includes: a body, which is arranged between both arms when a user takes an address posture, and has a reverse trapezoid-shape corresponding to a shape formed by the arms. The golf swing training apparatus controls changes in shapes of both arms, such as the interval between the arms becomes widened, bending of elbows, etc. when a golfer performs a swing motion in a swing training so as to guide his/her shoulder and waist to be smoothly turned. As a result, the golfer can learn a stable swing motion.