Projection optical system and image display apparatus

A projection optical system comprising:

• in order from a reduction side to a magnification side,
• an image forming unit configured to form an image thereon;
• a refraction optical system including a plurality of lenses;
• and
• a first reflecting surface and a second reflecting surface,
• wherein, when an optical axis shared by the largest number of lenses among optical lenses of the refraction optical system is defined as an optical axis of the projection optical system,
• a focal length of the refraction optical system is denoted by f,
• a direction parallel to the optical axis is defined by a Z axis direction,
• an arrangement direction of the first reflecting surface and the second reflecting surface is defined by a Y axis direction,
• a maximum value of a distance between the optical axis and an end portion of the image forming unit in the Y axis direction is denoted by Ymax,
• in a YZ plane which is a plane parallel to the Y axis direction and the Z axis direction, a maximum value D1 of a distance between an intersection of a light beam path from the image forming unit and the magnification-side surface of the lens which is arranged to be closest to the magnification side of the refraction optical system and the optical axis,
• a point H of which distance from the optical axis has a maximum value among the intersections of the light beam path and the first reflecting surface,
• a point F of which distance from the optical axis has a minimum value among the intersections of the light beam path and the second reflecting surface, and
• an angle θ1 between a line connecting the H and the F and the optical axis satisfies condition 1:
• 0<Ymax/f−1/tan θ1.