An image pickup apparatus for picking up an object comprises an image pickup device formed by arranging the photoelectric conversion elements constituting pixels in two-dimensional directions. A reading out circuit reads out from the image pickup device an electric signal obtained by photoelectric conversion with the image pickup device. A selecting portion selects from a plurality of reading out modes a reading out mode of the reading out circuit to carry out reading of the electric signal from the image pickup device. A memory circuit stores reading out positions of the image pickup device respectively in correspondence with the plurality of reading out modes. The reading out circuit reads out the electric signals from the image pickup device based on a reading out position corresponding to the reading out mode selected from the plurality of reading out modes by the selecting portion.