Abstract: A portable PSA oxygen generator that includes first and second filters for filtering inside air; a fan motor for passing through the air; a third filter for filtering the air intaken through the fan motor; a compressor assembly for compressing the air supplied; an oxygen concentrator for adding/eliminating oxygen to/from the compressed air supplied from the compressor assembly to generate the highly concentrated oxygen; an oxygen tank for storing the oxygen generated in the oxygen concentrator; an oxygen filter for filtering oxygen exhausted; a nitrogen filter for filtering and exhausting nitrogen; a pressure sensor installed inside the oxygen tank and outputting a signal indicating an internal pressure state; a failure alarming circuit made of buzzer connected with the pressure sensor in series, and a light emitting diode; a timer for limiting an operation time; an oxygen sensor for estimating the concentration of the oxygen exhausted through the oxygen filter; a control knob for controlling the concentratio