1. A method for counting objects using an image sensor and a depth sensor, the method comprising: acquiring an image by the image sensor, and acquiring a depth map from the depth sensor, the depth map indicating depth information on the subject in the image; acquiring edge information of objects of interest in the image; generating a corrected depth map by applying the edge information to the depth map; extracting depth patterns of the objects of interest from the corrected depth map; identifying at least one valid object among the objects of interest by comparing the extracted depth patterns and reference depth patterns stored in a database; and counting the identified valid object, wherein the step of extracting depth patterns of the objects of interest comprises: selecting one of the objects of interest; and extracting a depth pattern, based on projection information on virtual planes crossing the selected object, while moving toward a lower side of the selected object.