An image reading device capable of detecting foreign particles on a transparent member by including the transparent member, a conveyance unit that conveys an original document to the transparent member, a reading unit that reads via the transparent member an image of the original document being conveyed on the transparent member at multiple reading positions that exist with a prescribed distance therebetween along an original document conveyance direction, an output unit that outputs signals for different color components corresponding to each of the reading positions, a transparent member moving unit that moves the transparent member in a prescribed direction such that the original document slides over the transparent member while being conveyed to the reading positions during image reading, and a detector that detects noise components caused by foreign particles on the transparent member based on the output signals from the output unit.