An image recording/reproducing device for recording and/or reading an image through a two-dimensional scanning of an object with a light beam using a main scanning and a sub-scanning performed by a main scanning device and a subscanning device. the sub-scanning is stopped in an effective period of the main scanning so as to enable recording or reading of the image and is actuated in the blanking period other than the effective period. A very high precision of sub-scanning is attained without being influenced by any fluctuation in the speed of operation of the sub-scanning device.