To provide an original reading apparatus adopting a sheet-through system capable of automatically detecting dust and dirt even when the dust and the dirt or the like are deposited on contact glass and removing them without giving effect to other parts.

The original reading apparatus adopting the sheet-through system is configured to include: an original feed section 2 for supplying an original to an original read position 3; a light source 401 located to a side of the apparatus opposite to the original 1 with the original read position 3 inbetween and emitting light to the original 1 fed to the original read position; an image read means 5 for reading image information from the light reflected in the original 1; a foreign material detection means for detecting a foreign material on an optical path from the light source 401 to the image read means 5; and a cleaning means 8 for eliminating the foreign material, and the cleaning means 8 comprises a rotary brush or a rotary roller for eliminating dirt on the contact glass 6 and is located to the original feed section 2.