An image capturing apparatus, comprising: an image capturing element in which a plurality of pixels is formed and arranged in a two-dimensional array pattern and phase difference pixels are formed in a focus detection region within an effective pixel region; a photographing lens (21 a) which is installed in a stage preceding the image capturing element; and a control unit which is configured to analyze a captured image signal captured by the image capturing element, to obtain a phase difference amount from detection signals of plural first pixels and plural second pixels of the phase difference pixels that each make a pair, wherein the phase difference amount is an interval (a) between a light receiving distribution of the first pixels and a light receiving distribution of the second pixels, and to perform a focusing control of the photographing lens, characterized in that the control unit is further configured to calculate, as a sensitivity ratio, an average value of a ratio of a value of the light receiving sensitivity of a pixel other than the phase difference pixels that make the pair and a value of the light receiving sensitivity of the first pixel and a light receiving sensitivity of the second pixel, detected at a predetermined angle within the range of an incident angle of the photographing lens acquired at a plurality of points, and to correct a deviation in light receiving sensitivity between the two phase difference pixels that make the pair with the sensitivity ratio to correct the detection signals for acquiring the phase difference amount, wherein the range of the incident angle is a range of an incident angle corresponding to an F number of the photographing lens and an image height. an image capturing element in which a plurality of pixels is formed and arranged in a two-dimensional array pattern and phase difference pixels are formed in a focus detection region within an effective pixel region; a photographing lens (21 a) which is installed in a stage preceding the image capturing element; and a control unit which is configured to analyze a captured image signal captured by the image capturing element, to obtain a phase difference amount from detection signals of plural first pixels and plural second pixels of the phase difference pixels that each make a pair, wherein the phase difference amount is an interval (a) between a light receiving distribution of the first pixels and a light receiving distribution of the second pixels, and to perform a focusing control of the photographing lens, characterized in that the control unit is further configured to calculate, as a sensitivity ratio, an average value of a ratio of a value of the light receiving sensitivity of a pixel other than the phase difference pixels that make the pair and a value of the light receiving sensitivity of the first pixel and a light receiving sensitivity of the second pixel, detected at a predetermined angle within the range of an incident angle of the photographing lens acquired at a plurality of points, and to correct a deviation in light receiving sensitivity between the two phase difference pixels that make the pair with the sensitivity ratio to correct the detection signals for acquiring the phase difference amount, wherein the range of the incident angle is a range of an incident angle corresponding to an F number of the photographing lens and an image height.