To individually display contents of various abnormalities produced during operation and their time of outbreak.

Pressure sensors (22, 23) and oxygen concentration sensor (24) detect pressure of an oxygen enriched gas and oxygen concentration, respectively, and a flow-rate display (7) indicates set value of the flow rate at a flow regulator (20) that adjust feeding flow-rate of the oxygen enriched gas. Integrated time for use of an oxygen enricher is calculated by an integrated time calculation means (42) and displayed on an integrated time display (8). An abnormality sensing means (41) detects abnormality by comparing detected signal from each sensor with respective threshold value, and based on this detected result, an abnormality processing means (43) specifies contents of the abnormality and the integrated time for use at the time of detecting the abnormality and the specified contents of abnormality and integrated time for use are stored in a memory (44) as the data. The abnormality processing means (43) reads data from the memory (44) instructed by a display indication means (46) and lets the flow-rate display (7) and integrated time display (8) show the code indicating contents of the abnormality and the integrated time for use, respectively.