A respiratory assistance apparatus guides gas from a gas supply source to a connection part via an air inlet path. A check valve is disposed in the air inlet path, the check valve allowing the gas from the gas supply source to pass through to the connection part side and simultaneously preventing exhalation from the nose or mouth from flowing into the gas supply source side. An exhalation valve is preferably disposed in the air inlet path more to the connection part side than the check valve so as to discharge exhalation from the air inlet path by opening the exhalation valve during exhalation. This eases the burden of breathing of a patient and reduces contamination of the apparatus.
