A tool to evaluate the subjective wearing comfort of caps from the objective measurement of pressure was developed. Comfortable Fittability Index(C.F.I) and Holding Power(HP) were defined to represent the subjective wearing comfort of caps. As a preliminary step to define the Comfortable Fittability Index(C.F.I), average pressure, pressure distribution, standard deviation of pressure were obtained and subjective sensation were evaluated by wearing caps. Also Holding Power(HP) was estimated from wind tunnel testing. Two sets of caps were evaluated, one set made of elastic fabric(F-caps) and the other set made of non-elastic fabric(S-caps). F-caps begin to be taken off by the higher wind velocity and thus exhibited higher values of Holding Power. On the other hand, F-caps exerted lower average pressure, narrower pressure distribution, smaller standard deviation.