An image sensor driving apparatus extracts an image signal from an image sensor including a plurality of photoelectric conversion elements two-dimensionally arrayed, and includes a conversion unit which converts the image signal into digital data by performing offset correction for the image signal. The apparatus obtains digital data corresponding to a first sampling count by causing the conversion unit to process a reference voltage signal in accordance with a synchronization signal which determines an imaging frame rate, and obtains digital data corresponding to a second sampling count by causing the conversion unit to process a reference voltage signal every time extracting an image signal from a photoelectric conversion element group obtained by dividing a plurality of photoelectric conversion elements. The apparatus generates a correction value used for offset correction based on the obtained digital data corresponding to the first and second sampling counts.