A pressure swing adsorption-type oxygen enrichment device comprising: a plurality of adsorption cylinders (131, 132) filled with an adsorbent which selectively adsorbs nitrogen relative to oxygen; a compressor for supplying raw material air to the adsorption cylinders; means for performing an adsorption step for supplying compressed air to each of the adsorption cylinders and extracting an oxygen-enriched gas by sequentially switching flow channels between the compressor and each of the adsorption cylinders; means for performing a desorption step for depressurizing each of the adsorption cylinders and regenerating the adsorbent; means for performing a pressure equalizing step for communicating each of the adsorption cylinders; a flow-channel switching means (121, 122, 123, 124) for repeating a purge step in a specific timing, in which highly concentrated oxygen from the adsorption cylinder in the adsorption step is introduced into the adsorption cylinder in the desorption step; a flow setting means for supplying the oxygen-enriched gas to a user at a specific flow rate; an oxygen concentration sensor for detecting an oxygen concentration of the oxygen-enriched gas produced by the oxygen enrichment device; a temperature sensor for measuring a temperature of the device; characterised by a purge step control means which controls a length of a production and exhaust purge step so as to maximize the oxygen concentration by changing opening/closing timing of the flow-channel switching means when an output value of the oxygen concentration sensor is lower than a specified value, or the output value of the temperature sensor is out of a specific temperature range. a plurality of adsorption cylinders (131, 132) filled with an adsorbent which selectively adsorbs nitrogen relative to oxygen; a compressor for supplying raw material air to the adsorption cylinders; means for performing an adsorption step for supplying compressed air to each of the adsorption cylinders and extracting an oxygen-enriched gas by sequentially switching flow channels between the compressor and each of the adsorption cylinders; means for performing a desorption step for depressurizing each of the adsorption cylinders and regenerating the adsorbent; means for performing a pressure equalizing step for communicating each of the adsorption cylinders; a flow-channel switching means (121, 122, 123, 124) for repeating a purge step in a specific timing, in which highly concentrated oxygen from the adsorption cylinder in the adsorption step is introduced into the adsorption cylinder in the desorption step; a flow setting means for supplying the oxygen-enriched gas to a user at a specific flow rate; an oxygen concentration sensor for detecting an oxygen concentration of the oxygen-enriched gas produced by the oxygen enrichment device; a temperature sensor for measuring a temperature of the device; characterised by a purge step control means which controls a length of a production and exhaust purge step so as to maximize the oxygen concentration by changing opening/closing timing of the flow-channel switching means when an output value of the oxygen concentration sensor is lower than a specified value, or the output value of the temperature sensor is out of a specific temperature range.