The present disclosure provides an air-conditioning device and an air-conditioning system of an integrated heat exchanger, wherein an integrated heat exchanger for generating heating air or cooling air is used to generate air-conditioning air by utilizing cooling water, thereby securing cooling/heating efficiency. A decreased number of doors are used to adjust the temperature of air-conditioning air with regard to each mode, thus reducing the entire package. In addition, front and rear indoor spaces can be temperature-controlled individually, and comfort can be provided for each passenger seat.