To provide an image scanner provided with a detachable original mat and for clearly reading an optical image in the neighborhood of a reading start position of an original.

The image scanner comprises an original base mounting the original; a scanning part for reading the optical image of the original mounted on the original base; an original guide, projected from an outer edge of a reading start side of a base face of the original base and having a wall face contacting one end of the original; a swinging body, swingable up to an attitude covering the base face from the attitude opening the base face of the original base; an original mat swinging together with the swinging body, contacting the original mounted on the original base, during the attitude covering the base face of the original base by the swinging body and having a contact part covering the original mounted on the original base; and a positioning part, provided on the swinging body and for locking the end of the reading start side of the original mat so that one end of the reading start side of the contact part is located from the wall face of the original guide up to the outer edge of a reading range of the scanning part.