Image forming optical system, projection type display device, and imaging apparatus

An image forming optical system capable of forming an image on a conjugated plane on a reduction side as an intermediate image and re-forming the intermediate image as a magnified image on a conjugated plane on a magnification side, the image forming optical system comprising:

• a first adjustment group that moves along an optical axis in adjusting an image formation position of a region of the magnified image including a farthest point from the optical axis;
• and
• a second adjustment group that moves along the optical axis in adjusting an image formation position of a region of the magnified image including a nearest point from the optical axis,
• wherein an optical element disposed closest to the magnification side is a lens,
• the second adjustment group includes at least one positive lens, has a positive refractive power as a whole, and is disposed closest to the reduction side,
• assuming that an Abbe number of the positive lens based on a d line is vp, Conditional Expression (1) is satisfied, which is represented by
• vp<45 (1), and
• the first adjustment group is disposed to the magnification side than the intermediate image.