A document conveying apparatus includes a light source, a disk including a plurality of slits spaced apart with a predetermined interval in a rotation direction of the disk, which rotates in the rotation direction with a rotation speed as a document is conveyed, a light reception element provided at a position facing the light source with the disk interposed therebetween, a first signal generator for generating a first signal in accordance with light received by the light reception element, a second signal generator for generating a second signal obtained by removing, from the first signal, a noise component according to the rotation speed of the disk, and a controller for determining whether a document is conveyed by comparing the second signal with a predetermined threshold value.