An image forming device defines a reference line count, determines whether or not the number of lines of basic character strings to be formed which is arranged in an edit image forming memory area exceeds in number any of one or more n-th predetermined line counts, and calculates an n-th post-omission line count for notifying omission of lines from each n-th predetermined line count which the number of characters strings is determined to exceed by inserting an n-th predetermined line overflow notifying character string indicative of an excess in line count over each n-th predetermined line count between an end of a line of the basic character strings immediately before the count of lines of the basic character strings exceeds the n-th post omission line count and a head of the following line.