Disclosed is a method and a system for picking up an image by means of electrical charge generation and accumulation. In the disclosed method and system, to shorten the actual or substantial charge integration period, the charges are once cleared off as unwanted charges from the imaging part of an image pickup element before reading out of the wanted charges from the pickup element. The image pickup element further has a signal erasure part for erasing the excess charges generated at the imaging part. This erasure part, according the disclosed method and the system, is operated before the clearing off of the unwanted charges as well as after the clearing off of the unwanted charges. Thus, it is possible to prevent the unwanted charges from overflowing and affecting the wanted charges to be read out but also possible to reduce the stored quantity of the unwanted charges to be eliminated.