An image capturing apparatus includes an image sensor having an effective pixel area composed of effective pixels that photoelectrically convert an object image and a reference pixel area composed of reference pixels that output pixel signals to be a reference; a first calculation unit that calculates a standard deviation of the pixel signals output from the reference pixel area; a second calculation unit that calculates an integrated value of the pixel signals output from the reference pixel area; a third calculation unit that calculates a correction value for correcting pixel signals output from the effective pixel area, with use of the integrated value; a correction unit that corrects the pixel signals output from the effective pixel area, based on the correction value; and a determination unit that determines whether correction is to be performed by the correction unit, according to the standard deviation.