An image capturing system includes a signal correction unit which corrects a signal output from a defective pixel in an optical black region based on a signal output from a normal pixel. The optical black region has a plurality of pixel blocks. Each of the plurality of pixel blocks has a plurality of pixels each including one or more elements which have the same functions as in the remaining pixels and which have relative positions different from the remaining pixels. The signal correction unit corrects the signal output from the defective pixel in the optical black region based on a signal output from a normal pixel which is included in another pixel block different from the pixel block of the defective pixel in the optical black region and includes one or more elements having the same functions and same relative positions as in the defective pixel.