A laundry processing apparatus comprising: a cabinet having an installation space therein; a heat exchanger provided in the installation space of the cabinet and configured to transfer heat generated from exhaust air after heat-processing clothing; and a washing unit provided at a position inside the installation space which corresponds to an upper portion of the heat exchanger, the washing unit being configured to spray washing water on a front surface of the heat exchanger into which the exhaust air flows, wherein the washing unit comprises: a nozzle part provided at the upper portion of the heat exchanger in an inclined direction to guide the washing water toward the heat exchanger, the nozzle part having a first side connected to a water tube supplying the washing water and a second side extended to a position adjacent to the front surface of the heat exchanger; a front guide part (420, 423) provided at an opposite side of the nozzle part while being spaced apart therefrom, with the front surface of the heat exchanger interposed between the front guide part (420, 423) and the nozzle part, in which a protruding end of the front guide part (420, 423) is extended toward the front surface of the heat exchanger to guide the washing water discharged from the nozzle part toward the front surface of the heat exchanger; and a guide end protruding from an end of the nozzle part toward the front guide part (420, 423) so that the guide end guides the washing water toward the front surface of the heat exchanger, characterized in that the guide end is a nozzle guide end, the nozzle guide end protruding from the end of the nozzle part toward the front guide part, and a ratio X/L between a length X in which the nozzle guide end protrudes and a distance L between the nozzle guide end and the front guide part is between 0.04 to 0.15. a cabinet having an installation space therein; a heat exchanger provided in the installation space of the cabinet and configured to transfer heat generated from exhaust air after heat-processing clothing; and a washing unit provided at a position inside the installation space which corresponds to an upper portion of the heat exchanger, the washing unit being configured to spray washing water on a front surface of the heat exchanger into which the exhaust air flows, wherein the washing unit comprises: a nozzle part provided at the upper portion of the heat exchanger in an inclined direction to guide the washing water toward the heat exchanger, the nozzle part having a first side connected to a water tube supplying the washing water and a second side extended to a position adjacent to the front surface of the heat exchanger; a front guide part (420, 423) provided at an opposite side of the nozzle part while being spaced apart therefrom, with the front surface of the heat exchanger interposed between the front guide part (420, 423) and the nozzle part, in which a protruding end of the front guide part (420, 423) is extended toward the front surface of the heat exchanger to guide the washing water discharged from the nozzle part toward the front surface of the heat exchanger; and a guide end protruding from an end of the nozzle part toward the front guide part (420, 423) so that the guide end guides the washing water toward the front surface of the heat exchanger, characterized in that the guide end is a nozzle guide end, the nozzle guide end protruding from the end of the nozzle part toward the front guide part, and a ratio X/L between a length X in which the nozzle guide end protrudes and a distance L between the nozzle guide end and the front guide part is between 0.04 to 0.15. a nozzle part provided at the upper portion of the heat exchanger in an inclined direction to guide the washing water toward the heat exchanger, the nozzle part having a first side connected to a water tube supplying the washing water and a second side extended to a position adjacent to the front surface of the heat exchanger; a front guide part (420, 423) provided at an opposite side of the nozzle part while being spaced apart therefrom, with the front surface of the heat exchanger interposed between the front guide part (420, 423) and the nozzle part, in which a protruding end of the front guide part (420, 423) is extended toward the front surface of the heat exchanger to guide the washing water discharged from the nozzle part toward the front surface of the heat exchanger; and a guide end protruding from an end of the nozzle part toward the front guide part (420, 423) so that the guide end guides the washing water toward the front surface of the heat exchanger, characterized in that the guide end is a nozzle guide end, the nozzle guide end protruding from the end of the nozzle part toward the front guide part, and a ratio X/L between a length X in which the nozzle guide end protrudes and a distance L between the nozzle guide end and the front guide part is between 0.04 to 0.15.