PURPOSE: To simplify constitution of a mark reader and to improve accuracy for mark detection by using a photoelectric converting system for the mark reading together with a photoelectric converting system for character reading and further by using also an A/D convertor together with a buffer memory together.

CONSTITUTION: A card 1 with an entered mark M is moved in the arrow direction, and black optical information indicated by the mark M on the card 1 is received optically with a self-scanning type fixed pick up element 2 to be converted to an electric signal. After the converted electrical signal is amplified with an amplifier 3, a signal corresponding to the information on the card 1 is quantized in nultivalues to supplement blackness of the mark M on the card 1 digitally. When the digital signal is stored in a buffer memory 5, a piece of information for one mark column that exists in the range to be detected by a controlling signal stored in the memory 5. Next, data in the detected region for one mark column are read successively by the control signal from an address control circuit 6, and is stored in a memory 5, outputted from a mark identifying circuit 8 and is used commonly with a character reader.