An image inputting device is provided which is capable of making reliable and speedy detection of an indicia even for an nonstandard size postal matter. The postal matter, when having passed by a proximity detecting section, is radiated with ultraviolet light at specified timing from light radiating unit. When a postal matter is radiated with ultraviolet light, fluorescence is emitted from a phosphor formed on an indicia after being pumped. In the case where the indicia is an meter, when the meter passes by a fluorescence field of view, red fluorescence enters a fluorescence light receiving optical system along a fluorescence detecting optical axis. If the indicia is a postage stamp containing a substance that emits phosphorescence, when the postage stamp passes by a phosphorescence detecting field of view where no ultraviolet light is not emitted, green fluorescence enters a phosphorescence light receiving optical system along a phosphorescence detecting optical axis.