Abstract: A perfecting printer for performing a double-face printing operation of printing images on obverse and reverse faces of at least one sheet on the basis of a series of print data inputted from an external device and a method for controlling the double-face printing operation of the printer. The perfecting printer includes a page memory for storing as page data at least both of the first and second print data in the series of the print data, and a control unit for printing the first and second print data on both of the obverse and reverse faces of the sheet when it is judged that the page data to be printed on the reverse face of the sheet exists in the memory and promptly printing only the first print data on the obverse face of the sheet when it is judged that the page data to be printed on the reverse face of the sheet does not exist in the memory.