To provide a printer in which consumables, e.g. recording sheet and ink film, can be used up to the end.

When laterally elongate print corresponding to several sheets of standard print size is designated, residual quantity of color thermal recording sheets is measured prior to printing. When a sufficient quantity of color thermal recording sheets is left, printing is carried out as it is. When a small quantity of color thermal recording sheets is left, an image data is subjected to processing, e.g. trimming or demagnification, and printing is carried out on the remaining color thermal recording sheets.