An image sensing apparatus includes an image sensing device having a plurality of pixels, a smoothing unit that smoothes a dark image signal acquired with the image sensing device shielded from light; a subtraction unit that subtracts a second dark image signal from the dark image signal; an extraction unit that extracts, as a defective pixel of the image sensing device, a pixel of which an obtained difference is outside a preset range; and a correction unit that corrects, out of subject image signals output from the image sensing device, an image signal of the defective pixel extracted by the extracting unit, using an image signal of a pixel peripheral to the defective pixel.