An apparatus comprises a first camera (1), a second camera (2) and a third camera (3). The first camera (1) photographs a golf ball (B) from behind, the second camera (2) photographs the golf ball (B) from a head, and the third camera (3) photographs the golf ball (B) obliquely from ahead. At an early stage, position coordinates (x, z) of the golf ball (B) are calculated by a triangulation method from an angle of elevation of the golf ball (B) which is obtained by the first camera (1) and an angle of elevation of the golf ball (B) which is obtained by the second camera (2). Within a range in which the direction of advance of the golf ball (B) is coincident with the optical axis of the second camera (2), the position coordinates (x, z) of the golf ball (B) are calculated by the triangulation method from the angle of elevation of the golf ball (B) which is obtained by the first camera (1) and an angle of view of the golf ball (B) which is obtained by the third camera (3).