1. A golf swing-measuring system comprising a computer for capturing a colored moving image obtained by photographing a golfer who swings by gripping a golf club, wherein said computer selects and extracts one or more images each showing a swing posture as check-point images such as an address image, a take-back shaft 8 o'clock image, a take-back shaft 9 o'clock image, a take-back unskillful arm horizontal image, a top image, a downswing unskillful arm horizontal image, a downswing shaft 9 o'clock image, an impact image, a follow-through shaft 3 o'clock image, and a finish image and extracts from a large number of still images constituting said color moving image; and obtains coordinates of positions of attention-focused points that operate in said check-point images when said golfer swings.