1. A method of recognizing a user's dynamic organ for use in an electric-using apparatus, the method comprising: scanning a difference image, which reflects brightness difference between a target image and a comparative image that are inputted through an imaging element, using a window; generating a HOG (histograms of oriented gradients) descriptor of a region of the difference image that is scanned when it is judged that the scanned region includes a dynamic organ; measuring a resemblance value between the HOG descriptor of the scanned region and a HOG descriptor of a query template for a gesture of the dynamic organ; and judging that the scanned region includes the gesture of the dynamic organ when the resemblance value meets a predetermined condition, wherein the comparative image is one of frame images previous to the target image.