A projection optical apparatus capable of providing high image quality and having a reduced size. The projection optical apparatus comprises a light valve and a projection optical system including a first optical system(5) having a transmissive-ref ractive element and a second optical system (3') having a reflective-refractive element. An image formed on the light valve is projected by the projection optical system on a projection surface (4). The optical axis in the first optical system(5) is folded both vertically and horizontally. The first group (5A) of the first optical system is contained in a space (dead space) whose lower limit is defined by a lower edge of the second optical system(3') / thereby reducing the depth of the apparatus.
