A printer comprises: a vacuum table for supporting a jig which holds a medium; a printer head for discharging droplets; and a relative movement means for moving the printer head relative to the medium; a registration mark detection unit and barcode detection unit for acquiring holding platform information and support position information for the jig; and a controller for controlling the movement of the printer head by the relative movement means and controlling the discharge of droplets from the printer head on the basis of the holding platform information, the support position information and information pertaining to the desired pattern. As a result of this configuration, it is possible to generate image data without aligning the jig with a reference position on the vacuum table.