In processing a target sheet, raised letters (Braille) are formed by selectively driving a plurality of embossing pins arrayed in a direction perpendicular to a direction of feeding the target sheet such that the raised letters are represented in a projected bit pattern which is embossed at embossing points of a plurality of stages in two rows. Embossing operation is performed on the target sheet based on the emboss-inspection pattern which is made up of a repetition of the bit pattern. This emboss-inspection pattern facilitates to identify the cause of troubles, if any, in the embossing system.