PURPOSE: To provide an image sensor which is considerably small compared with a reduced optical system using a lens and a mirror and by which an optical axis can easily be adjusted at the time of making the density of an image high in a one-dimensional scanning-type image reader and to provide an image reader using it.

CONSTITUTION: The image sensor constituted in such a way that the one- dimensional image of an original 28 is guided to plural light-receiving sensor elements 17 through plural sheet-like optical waveguides 13 is used. The sensor light-receiving surface 17a of the light-receiving sensor element 17 is arranged in parallel to the optical path of the optical waveguide 13, and a long microprism 22 is arranged between the sensor light-receiving surface 17a and the optical waveguide 13. Light transmitted in the optical waveguide 13 is totally reflected on the sensor light-receiving surface 17a by the long microprism 22.