1. A drawing apparatus comprising: a controlling unit which adjusts a size of a design image formed by a image data, the image data includes position information of a key point which is predetermined set, the position information indicates a position of the key point in the design image, without changing (a) a ratio of a longitudinal length and a lateral length of the design image and (b) a relative position of the key point in the design image, generates an adjusted design image from the design image whose size has been adjusted, and fits, as a fitting process, the adjusted design image to a drawing region of a nail of a finger or a toe of a user; and a drawing unit which draws the adjusted design image on the drawing region fitted by the controlling unit, wherein the controlling unit sets an adjustment point in the drawing region at the same relative positions in the longitudinal and the lateral directions as the key point set on the design image, sets a longitudinal direction and a lateral direction of the adjusted design image to the longitudinal direction and the lateral direction of the drawing region, sets a size of the adjusted design image to minimum size which covers the whole area of the drawing region, and sets, in the fitting process, the adjusted design image to the drawing region at a position which the key point of the adjusted design image meets the adjustment point.