An imaging apparatus comprising: a photographing optical system (10, 10', 20, 21, 23); an image pickup device (16, 16') having a plurality of light-receiving elements two-dimensionally arranged, the image pickup device (16, 16') including a first light-receiving element and a second light-receiving element other than the first light-receiving element; image generating means (40, 25) configured to generate a first image from an imaging signal of the first light-receiving element and configured to generate a second image from an imaging signal of the second light-receiving element; and a first light-shielding member (10c, 13, 20d, 21c, 23d) having a predetermined width and formed in an optical member included in the photographing optical system, the first light-shielding member (10c, 13, 20d, 21c, 23d) dividing an entire pupil region of the photographing optical system into a first region and a second region, wherein the photographing optical system (10, 10', 20, 21, 23) is a multifocal lens having a first focal length of the first region and a focal length longer than the first focal length of the second region, characterized by: a second light-shielding member (12, 17a, 17b) different from the first light-shielding member and provided between the photographing optical system and each light-receiving element of the image pickup device, the second light-shielding member (12, 17a, 17b) being configured to make only a light beam passing through the first region enter the first light-receiving element and configured to make only a light beam passing through the second region enter the second light-receiving element, and wherein the first light-shielding member (10c, 13) divides the entire pupil region of the photographing optical system into the first region with a circular planar shape placed at a center of the optical member included in the photographing optical system, and the second region with an annular planar shape surrounding the first region. a photographing optical system (10, 10', 20, 21, 23); an image pickup device (16, 16') having a plurality of light-receiving elements two-dimensionally arranged, the image pickup device (16, 16') including a first light-receiving element and a second light-receiving element other than the first light-receiving element; image generating means (40, 25) configured to generate a first image from an imaging signal of the first light-receiving element and configured to generate a second image from an imaging signal of the second light-receiving element; and a first light-shielding member (10c, 13, 20d, 21c, 23d) having a predetermined width and formed in an optical member included in the photographing optical system, the first light-shielding member (10c, 13, 20d, 21c, 23d) dividing an entire pupil region of the photographing optical system into a first region and a second region, wherein the photographing optical system (10, 10', 20, 21, 23) is a multifocal lens having a first focal length of the first region and a focal length longer than the first focal length of the second region, characterized by: a second light-shielding member (12, 17a, 17b) different from the first light-shielding member and provided between the photographing optical system and each light-receiving element of the image pickup device, the second light-shielding member (12, 17a, 17b) being configured to make only a light beam passing through the first region enter the first light-receiving element and configured to make only a light beam passing through the second region enter the second light-receiving element, and wherein the first light-shielding member (10c, 13) divides the entire pupil region of the photographing optical system into the first region with a circular planar shape placed at a center of the optical member included in the photographing optical system, and the second region with an annular planar shape surrounding the first region. a second light-shielding member (12, 17a, 17b) different from the first light-shielding member and provided between the photographing optical system and each light-receiving element of the image pickup device, the second light-shielding member (12, 17a, 17b) being configured to make only a light beam passing through the first region enter the first light-receiving element and configured to make only a light beam passing through the second region enter the second light-receiving element, and wherein the first light-shielding member (10c, 13) divides the entire pupil region of the photographing optical system into the first region with a circular planar shape placed at a center of the optical member included in the photographing optical system, and the second region with an annular planar shape surrounding the first region.