After an end of exposure, a data level of OB signals that are imaging signals output from OB portion 400 are sampled by a CDS circuit 6 twice, to artificially generate two OB signals from each OB signal. Thereby, assuming that the total number of OB signals required to stabilize the black level in the clamp circuit 9 is n, the black level can be stabilized before it is started to output effective signals that are imaging signals from effective pixel portion 200 even if the number of OB signals output from the OB portion 400 is 1/n (in the case where pixel mixing or pixel thinning is performed, or in the case where the number of photoelectric conversion elements in the OB portion 400 is less than n). Accordingly, it is possible to prevent the image degradation by suppressing a wrong black level.