A respiratory assistance device 1 is used by a patient having a breathing problem to send gas to be inspired air into the respiratory tract of the patient. Specifically, the respiratory assistance device 1 includes: a blower 11 for taking in gas and sending out the gas into the respiratory tract of the patient; an upstream-side humidifier 10 for humidifying the gas to be introduced into the blower 11 on the upstream side of the blower 11; and a downstream-side humidifier 12 for humidifying the gas sent out from the blower 11 on the downstream side of the blower 11.This allows for the sufficient humidification of inspired air even when an inspiratory circuit from the blower is short.