Projection lens unit

A projection lens system 1 A enlarges and projects onto a screen 8 , via a plurality of lenses G 1 to G 16 , image light emitted from, a light source 4 and modulated by DMDs 3 r to 3 b. A movable lens barrel 25 holds the lens G 16 , having positive power, which is positioned closest to the DMDs 3 r to 3 b. An outer tube 24 holds the movable lens barrel 25 to enable movement in the optical axis direction. Through thermal deformation at the time of an increase in temperature, the bimetal member 27 moves the movable lens barrel 25 in the optical axis direction so as to recede from the image formation devices which are the DMDs 3 r to 3 b.