the entrance window 219 and reflected by the original document varies the current in the semiconductor layer 14 between the upper electrodes 216 217 a metal opaque layer 202 is connected like the opaque layer 112 to a suitable power source the charge accumulating area 212 is composed of a lower electrode wiring 214 a dielectric member consisting of an insulator layer 203 formed on said wiring 214 and the semiconductor 14 and an electrode wiring 217a formed on the semiconductor layer 14 and extended from the upper wiring 217 of the photosensor said charge accumulating area 212 is constructed in the same manner as so called mis metal insulator semiconductor capacitor it may be biased positively or negatively but the negative bias state of the lower electrodes wiring 214 provides a stable capacity and a stable frequency characteristic fig3 c shows the switch unit 213 of a thin film transistor tft structure including the transfer switch 213a and the discharge switch 213b wherein the transfer switch 213a is composed of a lower electrode wiring 224 constituting a gate electrode the insulator layer 203 constituting a gate insulator the semiconductor layer 14 an upper electrode wiring 225 constituting a source electrode and an upper electrode wiring 217 constituting a drain electrode as explained in the foregoing between the upper electrode wirings 217 225 226 and the photoconductive semiconductor layer 14 there is provided the n doped a si h layer 205 for forming the ohmic contact in the above explained image reading device shown in fig3 a 3b and 3c all the photosensor charge accumulating area transfer switch discharge switch and matrix wirings have the same multi layer structure.