PURPOSE: To shorten a read transfer time by eliminating a read transfer of an area having no printing data when a printing data is stored in only the central area with respect to a page memory and there is no printing data in upper and lower parts of that area.

CONSTITUTION: For example, assuming that a printing data is developed in order of address with respect to a page memory 16, contents of a current line position memory Lt at the time that a printing data corresponding to a line y21 is developed in a page memory developing processing will be positioned in a leading line of the printing data. Also, contents of the current line position memory Lt at the time that a printing data corresponding to a line y22 is developed will be positioned in an end line of the printing data. Thus, when a development of the printing data for 1 page with respect to the page memory 16 is completed and a driver interrupt processing is started, a leading line position memory TOPL will be larger than a line counter LNC with respect to a Y1 line from the leading line of the page memory 16 to the line y21, so that a data read transfer from the page memory 16 will be eliminated.