A respiratory assist device provided with a gas supply source and an air intake tube. A gas is supplied to a mask by way of the gas supply source and the air intake tube. A humidifier provided with a liquid supply unit, a humidifying member, a holding unit, a heating unit, and the like. The liquid supply unit supplies liquid to the humidifying member. The humidifying member is in a mode that encircles the internal periphery inside the air intake tube, and vaporizes the liquid supplied from the liquid supply unit. The holding unit holds the humidifying member so that the humidifying member is disposed continuously encircling or discontinuously encircling the internal periphery inside the air intake tube. The heating unit heats the interior of the air intake tube. A humidifier and a respiratory assist device having a simple structure, simple handling, and improved humidifying performance are thereby provided.
