For preventing occurrence of interference fringes derived from interference of light rays on a contact plane between a contact glass and a cover glass, and thus homogenizing an output wave that may otherwise undergo the adverse effect of interference fringes, a close-contact type image sensor includes a contact glass arranged to come into contact with a read surface of an original, a light source for irradiating light to the read surface, an image forming lens for converging light reflected from the read surface, an image sensor part for reading an image of the original formed on an image plane of the image forming lens, and a cover glass for fixing the light source and the image forming lens at respective predetermined positions in a housing, wherein an air layer is present between the contact glass and the cover glass.