In order to enable a medical worker to certainly and easily know whether a patient on a home oxygen therapy, who continues to inhale an oxygen-enriched gas at home, performs the inhalation as prescribed, a history of a supply condition of the oxygen-enriched gas supplied to the patient is recorded and held as supply history information, this supply history information is compared with a prescription of the oxygen therapy of the patient to generate patient's compliance information to indicate the degree to which the oxygen therapy is performed in accordance with the prescription, the oxygen concentrating apparatus is constructed to be portable, and a doctor can confirm the patient's compliance information at the time of going to a medical institution regularly.