The present invention provides oxygen concentrating device, restored in a very short period of time by selection optimal purge time corresponding with the deterioration state of adsorbent to the oxygen concentrating device of the control tool for the oxygen concentration for being suitable for treatment as having, it is characterized in that, below the oxygen concentration controlling value that the detected value of oxygen concentration sensor is oxygen concentration gas, in the case that the detected value of pressure sensor is more than the adsorption pressure that oxygen concentration significantly rises before and after the control for shortening purge time, carry out the moisture absorption deterioration judging of adsorbent, carry out the control for shortening the time of purging process compared with setting time.
