The present invention relates to a method for preparing an autologous skin cell agent for alleviating or treating skin defects. The method for preparing a therapeutic agent for alleviating or treating a skin defect using autologous skin cells according to the present invention, comprises the following steps: obtaining normal skin tissue from the patient's body; mincing the obtained tissue into cell units; and obtaining from the minced tissue matters, a skin cell line including keratinocytes, melanocytes and fibroblasts. The present invention excludes an enzyme-treating and/or an incubation step unlike conventional methods for preparing a therapeutic agent, therefore enabling a considerably easier and faster preparation and quicker application to an affected area.