To eliminate steaming which can be one of the causes of diaper rash by making fresh air flow into a diaper cup constantly or intermittently in an automatic excretion treatment apparatus which consists of the diaper cup to be fitted to the crotch of a person to be cared, a hose unit to be fitted to the diaper cup, and a suction unit to be fitted to the hose unit and a suction unit to be fitted to the hose unit and where a sensor inside of the diaper cup senses accumulation of excretions inside of the diaper cup, and the suction unit operates to suck the excretions taking a prescribed fixed time and to wash and dry the inside of the diaper cup and the private part of the person to be cared.

The apparatus is provided with an outside air release valve 31 and an outside air release pipe 32 to always take fresh outside air from a gap between the diaper cup 2 and the person to be cared 52 by operating a suction motor 9 constantly or intermittently excepting for the time of excretion treatment.