Imaging optical system, projection display device, and imaging apparatus

An imaging optical system consisting of, in order from a magnification side to a reduction side:

• a first optical system that includes a plurality of lenses;
• and
• a second optical system that includes a plurality of lenses,
• wherein the second optical system forms an intermediate image at a position conjugate to a reduction side imaging surface, and the first optical system re-forms the intermediate image on a magnification side imaging surface,
• wherein the first optical system consists of, in order from the magnification side to the reduction side, a first A lens group that has a positive refractive power as a whole, and a first B lens group that has a positive refractive power as a whole and is separated from the first A lens group by a maximum air gap on an optical axis between lens surfaces in the first optical system,
• wherein the second optical system consists of, in order from the magnification side to the reduction side, a second A lens group that has a positive refractive power as a whole, and a second B lens group that has a positive refractive power as a whole and is separated from the second A lens group by a maximum air gap on the optical axis between lens surfaces in the second optical system,
• wherein a negative lens included in the first B lens group is only a lens which is disposed to be closest to the magnification side in the first B lens group,
• wherein a negative lens included in the second A lens group is only a lens which is disposed to be closest to the magnification side in the second A lens group, and
• wherein a negative lens included in the second B lens group is only a lens which is disposed to be closest to the magnification side in the second B lens group.