The purpose of this study was to investigate the effects of flame-proof clothing on physiological responses and subjective sensation. We measured rectal temperatures, local skin temperature, clothing microclimate, blood pressure, heart rate, body weight loss and subjective sensation during 90 minutes (30 min of rest, 45 min of exercise and 15 min of recovery periods). Seven male subjects wore flame-proof clothing or reformed flame-proof clothing under the environmental condition of $35{pm}1^{circ}C$, $45{pm}5%$ RH and $25{pm}1^{circ}C$, $50{pm}5%$ RH. The results of this study were as follows; Rectal temperature, mean skin temperature, clothing microclimate and blood pressure were significantly lower levels in reformed flame-proof clothing. Heart rate and body weight loss were also showed lower levels. Subjects replied less hot, less uncomfortable and less wet in wearing a reformed flame-proof clothing. Our present results suggest that the ventilation through of gusset in underarm seam and zipper in sideseam of slacks are qualitatively useful for physiological needs.