To provide an image scanner that prevents occurrence of an uneven image by detecting the light quantity of a light source for lighting an original face and controlling the light quantity from the light source at a constant value based on the detection result.

An image scanner is provided with a linear light source 15 for lighting an original face, a reflector 18 placed at a position where a light at the end of the linear light source is directly made incident, a photoelectric conversion element array 14 having an original read-out element 14A onto which the reflected light from the original face is made incident and having a light quantity detecting element 14B onto which the reflecting light from the reflector 18 is made incident, and a light quantity control section that controls the light quantity of the light source 15 at a constant value corresponding to the output of the light quantity detecting element 14B.