To provide a nail printing apparatus and a printing control method which automatically print a design similar to, to the utmost extent, the image of a design image selected by a user on a nail region of the user without bothering the user.

Size data, position data, and image data are stored in a design data holding unit, corresponding to each of a plurality of design parts dp constituting the design image. A part layout calculation unit calculates the print size and print position of each of the design parts dp according to the size data and position data of each of the design parts dp included in the design image selected by the user, and according to an area and vertical and transverse lengths of the nail region of the user. Printing data for applying printing on the nail region are generated on the basis of the print size, the print position, and the image data of each of the design parts, and a printing unit applies printing on the nail region.