Magnification optical system

A magnification optical system that enlarges an image of an object, the magnification optical system comprising:

• a first optical system including a plurality of lens groups;
• a second optical system including a curved mirror that reflects light received from the first optical system;
• and
• a focus structure, wherein
• the plurality of lens groups includes, in order from an object side to an enlarged side,
• a first lens group,
• a second lens group,
• a third lens group, and
• a fourth lens group,
• the focus structure does not move the first lens group and the curved mirror, and
• the focus structure moves the third lens group and the fourth lens group to change an interval between the third lens group and the fourth lens group.