An image reading apparatus that detects failure in the white LEDs constituting a white LED array. Failure in the white LEDs is detected by comparison between a prescribed current threshold and the current running in the LED array detected by an image reading apparatus controller when the white LED array composed of plural LED blocks connected in parallel, each LED block being composed of plural LEDs connected in series, is powered for failure detection. This failure check is conducted by checking LEDs for failure in each of the LED blocks constituting the LED array. Image reading is not permitted when faulty LEDs are detected in two neighboring LED blocks.