Projection optical system and projection display device

A projection display device, comprising:

• a projection optical system for enlarging and projecting an image on an imager onto a projection plane,
• the projection optical system including:
• a first refracting optical system having a plurality of lenses;
• a first reflecting optical system having a positive optical power and disposed on a side of a projection port with respect to an optical axis of the first refracting optical system to reflect light incident through the first refracting optical system in a direction opposite to the side of the projection port;
• and
• a second reflecting optical system for reflecting the light reflected on the first reflecting optical system toward the projection port.