PURPOSE: To obtain images having high quality in a matrix while averting the saturation of photodiodes PDs by eliminating the need for emptying a shift register many times and storing and accumulating the measured charges at the time of reading the charge quantities supplied from the matrix of the PDs.

CONSTITUTION: The shift register 10 has the stages common to n stages continuous for each of the respective PDs 1 and charge transfer means 16 for creating receptive potential wells in correspondence to the register and the PDs. The n-1 stage in the n stages forms n-1 pieces of the intermediate potential wells between the potential wells corresponding to the adjacent PDs in the same rows or columns as the rows or columns as the corresponding potential wells. The charge quantities of the wells for respective charge storage are considered in the register 10 after the accumulated charges and bias charges are transferred n times to the shift register 10 and are shifted n-1 times. A bias charge implanting means 17 has the charges inquired by the potential wells after the bias charges are implanted to all the wells of the register 10 so that the charge quantities to be read for the respective PDs are after n times of transfer of the accumulated charges. The high-quality matrix images are obtd. by averting the saturation of the PDs by such constitution.