The main subject of this study is to clarify the effects of varying skin temperature due to types of clothing on heat-stress during brisk walking exercise. For that purpose, this paper analyzed thermoregulatory responses to wearing a sweat suit and a non-sweat suit during exercise in a hot environment. Eight female subjects performed 60-min brisk walking in a room maintained at 26.6±0.7℃ (wet-bulb globe temperature, WBGT). The experiment was performed under two conditions, with two sets of clothing. Increases in tympanic temperature, RPE(rating of perceived exertion), thirst level and total sweat loss at the end of exercise were significantly (p＜.05) higher in sweat suit than in non-sweat suit. Heart rates during exercise were higher in sweat suit than in non-sweat suit, but there was no significant difference in both groups. The elevation of tympanic temperature at the end of exercise was 1.25±0.12℃ in the sweat suit group, whereas 0.69±0.23℃ in the non-sweat suit group. Mean skin temperature was significantly (p＜.05) higher from 15-min to 35-min during exercise in sweat suit than in non-sweat suit. Thermal sensation was significantly (p＜.05) higher from 10-min to 25-min during exercise in sweat suit than in non-sweat suit. Under two conditions at the end of exercise, weight loss and thirst level were correlated with each other (r=0.69, r=0.66). RPE was correlated with thermal sensation (r=0.72, r=0.49) for two conditions respectively. These results show that a sweat suit may cause core temperature elevation due to ineffective sweating during brisk walking exercise under hot conditions.