PURPOSE: To improve packing between a projection tube and a bracket and to reduce the leakage of a cooling solution due to the inserting and holding of an foreign substance such as dust.

CONSTITUTION: The projection tube 1 and a concave lens 3 are fixed on a bracket 2 consisting of a material having high heat transmissivity respectively through packing 10, 11 and optically connected to each other. A cooling solution is sealed in a cooling room 2a of a bracket 2 arranged between the tube 1 and the lens 3. The packing 10 has grooves on both the sides of a bracket contact face and a projection tube contact face and consists of an enlarging part to be engaged with a ring-like groove of the bracket 2 and a flat flange part formed so as to be continued to the enlarging part.