To provide an image reader which can increase its reading speed without deteriorating the resolution by reading the images in parallel to each other between the sensors A and B placed in parallel to each other in the subscanning direction and keeping the difference of optical signal storage periods between both sensors to read the even and odd lines separately from each other.

An original put on an original glass board 1 is scanned by a light source 2 moving in the subscanning direction, and the reflected light of the original is led to a lens 7 by a movable mirror 5 consisting of mirrors 3 and 4 and a mirror 6 of the light source 2. The original image sent from the lens 7 is divided into two parts by a half mirror 8 and forms the images through the CCD line sensors 9 and 10 having their element trains arranged in parallel to each other in the subscanning direction. The difference of optical signal storage periods is secured every line phase between both sensors 9 and 10, and the even and odd lines are read separately from each other by the sensors 9 and 10. Thus the image reading speed is doubled in the subscanning direction compared with only a single sensor. Then the image data are synthesized between both sensors 9 and 10, and the image reading speed of an image reader is increased without deteriorating the resolution.