METHOD OF SELECTING MATCHING TYPE OF SIZE OF HELMET, AND METHOD OF ADJUSTING SIZE OF HELMET BY USING SUCH SELECTING METHOD

The back-and-forth length and right-to-left width of the head of a helmet wearer are input to a computer and data-processed, so that the type of a helmet size that matches the helmet wearer and its matching data are selected and displayed on a computer window or the like. A helmet of a size that matches the helmet wearer can be obtained easily together with its matching data. Even when a helmet wearer having a head shape different from an average human head shape is to wear a helmet, the helmet can be matched to the head of the helmet wearer substantially optimally by only performing comparatively simple size adjusting operation in accordance with the matching data.