An image processing device comprising a fading information generation unit (35a; 35b; 38) configured to generate fading information indicating fading of a color filter on a basis of comparison target information based on an image signal generated by an image capturing unit (20, 21) using the color filter and fading determination reference information, a color information generation unit (32a; 32b; 32c) configured to generate color information from the image signal and use the color information as the comparison target information; and a color information comparison unit (33a; 33b) configured to use color information in a case where there is no fading of the color filter as the fading determination reference information and compare the comparison target information with the fading determination reference information, wherein the fading information generation unit (35a; 35b; 38) generates the fading information on a basis of a comparison result by the color information comparison unit, wherein the image processing device further comprises: a comparison area detection unit configured to detect a comparison area indicating an image area of a fading determination object on a basis of the image signal, wherein the color information generation unit (32a; 32b; 32c) generates the color information from the image signal of the comparison area detected by the comparison area detection unit and uses the color information as the comparison target information, and the color information comparison unit (33a; 33b) uses the color information of the fading determination object as the fading determination reference information, characterized in that the fading information generation unit (35a; 35b; 38) estimates a fading level on a basis of the comparison result by the color information comparison unit (33a; 33b) and notifies the comparison area detection unit of the fading level, and the comparison area detection unit detects the comparison area with precision according to the fading level estimated by the fading information generation unit. a fading information generation unit (35a; 35b; 38) configured to generate fading information indicating fading of a color filter on a basis of comparison target information based on an image signal generated by an image capturing unit (20, 21) using the color filter and fading determination reference information, a color information generation unit (32a; 32b; 32c) configured to generate color information from the image signal and use the color information as the comparison target information; and a color information comparison unit (33a; 33b) configured to use color information in a case where there is no fading of the color filter as the fading determination reference information and compare the comparison target information with the fading determination reference information, wherein the fading information generation unit (35a; 35b; 38) generates the fading information on a basis of a comparison result by the color information comparison unit, wherein the image processing device further comprises: a comparison area detection unit configured to detect a comparison area indicating an image area of a fading determination object on a basis of the image signal, wherein the color information generation unit (32a; 32b; 32c) generates the color information from the image signal of the comparison area detected by the comparison area detection unit and uses the color information as the comparison target information, and the color information comparison unit (33a; 33b) uses the color information of the fading determination object as the fading determination reference information, characterized in that the fading information generation unit (35a; 35b; 38) estimates a fading level on a basis of the comparison result by the color information comparison unit (33a; 33b) and notifies the comparison area detection unit of the fading level, and the comparison area detection unit detects the comparison area with precision according to the fading level estimated by the fading information generation unit. a comparison area detection unit configured to detect a comparison area indicating an image area of a fading determination object on a basis of the image signal, wherein the color information generation unit (32a; 32b; 32c) generates the color information from the image signal of the comparison area detected by the comparison area detection unit and uses the color information as the comparison target information, and the color information comparison unit (33a; 33b) uses the color information of the fading determination object as the fading determination reference information, characterized in that the fading information generation unit (35a; 35b; 38) estimates a fading level on a basis of the comparison result by the color information comparison unit (33a; 33b) and notifies the comparison area detection unit of the fading level, and the comparison area detection unit detects the comparison area with precision according to the fading level estimated by the fading information generation unit.