The purpose of this paper was to design the sizing system of the head gears which would be a guide of men for selecting their head gears of suitable size. This study was carried out on 214 men and was done by cluster analysis with two variables(head circumference and bitragus to vertex arc length). The results were as follows : First, most of measurements were larger in men than in women. Second, the suitable numbers of size were found that 5 sizes were proper by cluster analysis with two variables. After the design of sizing system, the cover ratio was investigated in order to decide whether it is proper or not. Third, in the cover ratio, the 5 sizes were the highest in all of them.