An information medium reading device may include a magnetic head to read magnetic datum and output an analog magnetic signal; an image sensor to take a photo of image datum and output an analog image signal; an analog switch unit to select one of the analog magnetic signal and the analog image signal and output the selected one; an analog front-end unit having an analog/digital (A/D) conversion function for converting an analog signal to a digital signal, while using a voltage according to a black reference voltage at the time of image reading, as a bottom voltage, within a predetermined converted voltage range; a level adjustment unit to make a level adjustment; and a timing control unit. The analog magnetic signal may be input into the analog front-end unit, and an A/D conversion may be carried out for converting an analog signal to a digital signal.