To highly speedily process the judgement whether the result of printing is success or failure by setting the resolving power of a recognition device so that the printing dot information of a marker and the binarized dot information of the picture recognizing device are corresponded in one to one, executing the theoretical product calculation of the binarized dot of the same coordinate with the burning dot of the liquid crystal mask.

Printing letters and an image of a printed work 30 are read with a camera 41. Data is digitized with a binarized circuit 42 and taken in a picture memory 43. A printing dot information 47 is drawn out from a mask controller 11 and it is compared with the data 48 of the memory 43 with a computing element 45. The theoretical product calculation of the burning dot of the printing dot information 47 and the dot of the information 48 as the same coordinate is executed. When all the calculated results are made as '1', it is made as perfect success, when the number being as '0' is made more than a setting number, it is judged as being failure. Against all the dot of the picture memory 43, because arithmetic processing is made enough without requiring, so processing is executed highly speedily and the recognition device with a cheap price is realized.