This study was carried out to investigate the effects of wearing disposable diaper with the endothermic agent on thermoregulatory responses of infant. Five healthy female infants, aged about 5 months, were taken as a subject of this experiment. Experimental diapers were six kinds of disposable diaper constructed of nonwoven, tissue, fluff pulp, super absorbent polymer, back sheet film, leg elastic, and 0g urea(A), ig urea(B), 2g urea(C), 3g urea(D), 4g urea(E), 5g urea(F) respectively. Urea(98% or over purity) was used as an endothermic agent. Experiment was proceeded while infants were sleeping, at 27.5±0.5℃, 50±5％R.H., 0.04m/sec. Each disposable diaper`s properties was tested. During the experiment, rectal temperature, skin temperature of 9 areas, temperature inside the disposable diapers were measured. The results were as follows; 1) There was not significant. difference among the diapers in absorption capacity, retention capacity and rewet(p=0.05). The absorption under load was showed to A, B < C, D < E < F, and the absorption rate was showed to A < B, C < D, F, E (p=0.05). 2) Rectal temperature was showed to D, F < E, B, C < A, and gradually decreased in all diapers except A. 3) The more endothermic agent inserted in diapers; Extremities and mean skin temperature were significantly lower(p=0.05). 4) The less endothermic agent inserted in diapers, temperature and humidity inside the disposable diapers were significantly higher(p=0.05).