To provide a respiration aid device with a size suitable for carrying.

The respiration aid device has a pump 11 for the air compression, a buffer tank 3 for accumulating the compressed air 6, a link tube 5 for supplying the compressed air to a mask 4 for respiration from the buffer tank 3 and a control valve 14 which enables the adjustment of the pressure of the mask 4 by releasing a part of the compressed air. In the respiration aid device 1, the use of the buffer tank 3 enables the safe supply of the quantity of air intake sufficient for the intermittent respiration with a small-capacity pump 11 and the employment of the small-capacity pump 11 can reduce the size of the device significantly. The use of the buffer tank 3 with a bellows structure makes the device more compact in the non-use size to facilitate the carrying thereof.