A projection lens unit compensates for thermal expansion and contraction. The unit comprises a coupler at the front surface of a CRT, a lens unit body for projecting an image onto a screen by controlling and magnifying the light from the CRT, a plurality of legs secured to the coupler for supporting the lens unit body at more than three points, a slide mechanism (latch arms and latch engaging slots provided between the legs and the lens unit body for slidably supporting the legs for movement along the optical axis relative to the lens unit body, and expansion/contraction bars provided between the legs and the lens unit body for compensating for the thermally induced expansion/contraction, with one end engaged with a leg and the other end engaged with the base of the lens unit body.