An image forming device includes: a storing unit that stores image data of plural pages, an operating unit and a setting unit that sets the number of sheets used for N-up printing of the plural pages. A determining unit determines the number of pages aggregated on a single side of a single sheet when N-up printing is performed using the number of sheets set by the setting unit. An orientation selecting unit selects a paper orientation that lowers a reduction ratio of a page when N-up printing is performed on the number of pages determined by the determining unit. An image forming unit uses the image data stored in the storing unit to form images of the plural pages onto sheets according to the number of sheets set by the setting unit, the number of pages determined by the determining unit, and the selected paper orientation.