An imaging device comprising: an image sensor including a plurality of imaging pixels and a plurality of focus detection pixels, each of the focus detection pixels having an opening position of a light receiving portion different from each of the imaging pixels; a read-out section which is configured to mix and read out pixel signals of the image sensor, and output a mixed pixel output; and a pixel correction section (171, 173) which is configured to correct the mixed pixel output, characterized in that in the image sensor, a first focus detection pixel is arranged at a position corresponding to a first color filter of the imaging pixel and a second focus detection pixel is arranged at a position corresponding to a second color filter of a different color to the first color filter of the imaging pixel, wherein in mixing and reading out the outputs of the imaging pixels corresponding to the first color filter, the read-out section is configured to mix a plurality of pixel signals including the output of the first focus detection pixel and read out a first mixed pixel output, while in mixing and reading out the outputs of the imaging pixels corresponding to the second color filter, the read-out section is configured to mix a plurality of pixel signals without including the output of the second focus detection pixel and read out a second mixed pixel output, and wherein the pixel correction section (171, 173) is configured to correct the output value of the first mixed pixel output, and is configured to not correct the output value of the second mixed pixel output, the first focus detection pixel is a pixel having the opening position shifted in a left direction or in a right direction relative to the opening position of the imaging pixel, and the second focus detection pixel is a pixel having the opening position shifted to an upper or lower direction relative to the opening position of the imaging pixel, and the pixel correction section (171, 173) is configured to correct the output value of the first mixed pixel output based on correction gain that is based on a light-shielding rate of the first focus detection pixel and a number of mixed pixels. an image sensor including a plurality of imaging pixels and a plurality of focus detection pixels, each of the focus detection pixels having an opening position of a light receiving portion different from each of the imaging pixels; a read-out section which is configured to mix and read out pixel signals of the image sensor, and output a mixed pixel output; and a pixel correction section (171, 173) which is configured to correct the mixed pixel output, characterized in that in the image sensor, a first focus detection pixel is arranged at a position corresponding to a first color filter of the imaging pixel and a second focus detection pixel is arranged at a position corresponding to a second color filter of a different color to the first color filter of the imaging pixel, wherein in mixing and reading out the outputs of the imaging pixels corresponding to the first color filter, the read-out section is configured to mix a plurality of pixel signals including the output of the first focus detection pixel and read out a first mixed pixel output, while in mixing and reading out the outputs of the imaging pixels corresponding to the second color filter, the read-out section is configured to mix a plurality of pixel signals without including the output of the second focus detection pixel and read out a second mixed pixel output, and wherein the pixel correction section (171, 173) is configured to correct the output value of the first mixed pixel output, and is configured to not correct the output value of the second mixed pixel output, the first focus detection pixel is a pixel having the opening position shifted in a left direction or in a right direction relative to the opening position of the imaging pixel, and the second focus detection pixel is a pixel having the opening position shifted to an upper or lower direction relative to the opening position of the imaging pixel, and the pixel correction section (171, 173) is configured to correct the output value of the first mixed pixel output based on correction gain that is based on a light-shielding rate of the first focus detection pixel and a number of mixed pixels.