Conventionally, respiratory assistance device applied to Auto CPAP respiratory therapy or the like includes a long air tube which supplies pressurized air thus being difficult to handle, and there is a problem in that the degree of freedom of the head is restricted thus interrupting sleep. The present invention provides a respiratory assistance device suitable for Auto CPAP respiratory therapy. The respiratory assistance device includes: a blower device including a blower configured to generate pressurized air; an operation device including an operation interface configured to control the blower; wireless or wired communication means configured to connect the blower device and the operation device to each other; an attachment part configured to be attached to a head of a patient so as to supply the pressurized air to an airway of the patient; and an air tube through which the pressurized air is introduced into the attachment part from the blower device, wherein the blower device is accommodated in a blower device casing, and the operation device is accommodated in an operation device casing separate from the blower device casing.