To provide an artificial respiration system which can support spontaneous breathing effort of a patient detected during high frequency vibration oscillation.

An artificial respirator system further has detectors 14, 15, 16 to monitor gas pressure and/or gas flow rate, to detect fluctuation of the gas pressure and the gas flow rate which are not drawn out from an induced high frequency, and to output a trigger signal corresponding to detected fluctuation showing spontaneous breathing effort during high frequency vibration artificial respirators 1, 4, 5, 6 are in motion. The gas supplying part 7 can act based on reception of a trigger signal 13 and supplies breathing gas to patient's circuits 2, 3 at a level to support the spontaneous breathing effort.