Expansion of the dynamic range was difficult in conventional amplifying photoelectric conversion devices designed to have a large gain because, when used for high input light intensity, the electric current exceeds the electric current capacity of a near-minimum sized transistor obtained with the design rules. Also, in conventional photoelectric conversion devices, techniques for varying the electric signal outputs in real-time at the device level are necessary for real-time import of observation targets or images having a high contrast ratio and for visualization of local areas in real-time. In order to solve this problem, the present invention provides a gain varying method, a variable gain photoelectric conversion device, a photoelectric conversion cell, a photoelectric conversion array, a read-out method thereof, and a circuit therefor in which amplifying photoelectric conversion devices and field-effect transistors are combined.