A shaft behavior automatic measuring system 2 according to the present invention includes a metal member 14 provided on a surface of a shaft 8 in a golf club 4, and a radar device 6 to be a Doppler radar. The radar device 6 has at least one transmitting portion for emitting a radar wave to the metal member 14 in the golf club 4 during a swing and at least three receiving portions 16 for receiving the radar wave reflected from the metal member 14. The shaft behavior automatic measuring system 2 includes a calculating portion for calculating three-dimensional coordinates of the metal member 14 based on a signal received by the at least three receiving portions 16. A coating material containing metal powder, a resin sheet containing metal powder, a metallic foil and a metallic thin film are taken as an example of the metal member 14.