An image processing method for detecting a target, includes: an image acquiring unit for acquiring depth information of an image; a histogram creating unit for creating a histogram on the depth information of the image; a critical value setting unit for setting a critical value of the depth information for detecting a region of a detection object from the image; an image processing unit for extracting a region of the detection object from the image by using the set critical value of the depth information; a data verifying unit for verifying whether the extracted region of the detection object corresponds to the target; and a storage unit for storing the extracted region of the detection object. A target is detected based on depth information of an image.