An imaging apparatus is provided, which improves correction accuracy at the time of pixel addition reading and scarcely deteriorates in resolution of the image data. This apparatus comprises: a conversion unit comprising a plurality of unit-pixels and converting an incident radiation or a light into pixel information; a signal processing unit capable of reading the pixel information for each unit-pixel, or capable of reading additional added pixel information for a plurality of unit-pixels, based on a control from a control unit for controlling a driving of the conversion unit according to a plurality of operation modes; a storage unit for storing a plurality of correction informations according to the plurality of operating modes; and a correction unit for performing the correction of the pixel information based on the correction information extracted from the plurality of correct informations according to the operation mode.