Abstract: An image scanning device with a rotatable reflection mirror arranged in an optical scanning module thereof for establishing either a reflective or transparent scanning optical path is disclosed. The optical scanning module includes a first focusing lens, a second focusing lens, an image sensing module, a plurality of fixed reflective optical path mirrors, a plurality of fixed transparent optical path mirrors, and a rotatable reflection mirror. At scanning a reflective document, the rotatable reflection mirror is rotated to a first reflection position. A light beam from a first light source projects to the reflective document. The image of the reflective document is reflected by the rotatable reflection mirror and the fixed reflective optical path mirrors, and then received by the image sensing module through the first focusing lens. At scanning a transparent document, the rotatable reflection mirror is rotated to a second reflection position.