PURPOSE: To prevent a module from being mis-fitted on a printed-circuit board where a plurality of modules are fitted onto the printed-circuit board.

CONSTITUTION: Graphic marks 22, 52, and 62 are printed at each module-fitting portion of a printed-circuit board 10. Also, same graphic marks 32, 54, and 64 corresponding to the graphic marks 22, 52, and 62 are printed at modules 30, 50, and 60. The graphic marks can be distinguished from other modules according to a length of a band-shaped mark and a combination of hollowed or color painting. Therefore, when fitting the modules 30, 50, and 60, graphic marks 32, 54, and 64 are allowed to respond to the graphic marks 22, 52, and 62, respectively for fitting accurately, thus preventing fitting mistakes from occurring.