PURPOSE: To hit a golf ball from either one of right and left hitting positions, and at the same time, detect easily a hitting-up angle and right and left hitting- out angles of the flying ball in relation to the horizontal surface without using any complex device such as a CCD camera.

CONSTITUTION: A number of reflection type optical sensors D1-D21 which detect, when a flying ball has passed a measuring surface supported at the front of a teeing-up position, the longitudinal and latitudinal positions of its passing point as the coordinates of two dimensions, are embedded at a floor so that light may be irradiated from at least two directions in read to the points P of respective coordinates, and an operation device 10 which calculates the coordinates of the passing point of the golf ball on the basis of the output signals of plural optical sensors D1-D21 that have detected reflection light from the golf ball, is equipped.