To provide an image forming device provided with an ADF (Automatic Document Feeder) that detects a reflected light quantity while rotating a transport roller in the case of adjusting the read position for image forming so as to prevent the read position from being erroneously detected due to noise caused by dust and dirt when dust or dirt or the like is deposited on part of the surface of the roller.

The image forming device is configured such that the light source of the image forming device emits light to an ADF transport roller, a light quantity detection means detects the light quantity reflected from the transport roller by moving an original reader forward/backward, the read position for the image forming is adjusted by the value of the reflected light quantity detected by the light quantity detection means, and the reflected light quantity is detected while the transport roller is driven.