1. A defective pixel data correcting apparatus for correcting defective pixel data output from a defective pixel of an image sensor, the defective pixel data contained in image data captured using the image sensor comprising a plurality of pixels, the defective pixel data correcting apparatus comprising: a first storage unit adapted to store defective pixel information containing a type and a defective output level of a defective pixel, for each defective pixel included in the plurality of pixels; a second storage unit adapted to store at least one correction table in which types of the defective pixels, image capturing conditions, and defective output levels to be subjected to correction are associated with each other; a determination unit adapted to determine whether or not the defective pixel data is to be corrected, based on the defective pixel information and the correction table; and a correction unit adapted to correct the defective pixel data that is determined, by the determination unit, to be corrected.