The present invention provides an image reader apparatus capable of obtaining an image having stable brightness while suppressing an increase of the cost of the apparatus. The image reader apparatus 1 for reading an image on a document 2 being fed and outputting an image signal includes a synchronization signal generation circuit 4 for generating a synchronization signal SS synchronous with a feed timing and a feed cycle of the document 2, a CCD 6 for reading an image on the document 2 in synchronism with the synchronization signal SS, an LED 9 for emitting white light, and a lighting control circuit 7 for turning the LED 9 on in synchronism with the synchronization signal SS and turning the light source off so that a lighting period is equalized for each line irrespective of a variation of the feed cycle of the document 2. The lighting control circuit 7 turns the LED 9 off so that the lighting period of the LED 9 is equal to a predetermined preset period.