SOLID STATE LASER

PROBLEM TO BE SOLVED: To suppress deterioration in the quality of light through simple improvement in the arrangement of a channel. SOLUTION: The solid state laser comprises a solid state amplification medium 1 having a light exit face 6 intersecting a reference optical axis L at an acute angle, and a channel forming body 2 for passing a cooling medium. The solid state amplification medium 1 has a first outer surface 5-1 intersecting the light exit face 6 at an acute angle and being cooled by cooling medium, and a second outer surface 5-2 intersecting the light exit face 6 at an obtuse angle and being cooled by the cooling medium. The channel forming body 2 has an incident channel 9 for leading the cooling medium to the first outer surface 5-1 in a first outer end region on the outer end side of the first outer surface 5-1 in the direction of reference optical axis. The first outer end region extends substantially to the outer end of the first outer surface 5-1 and the cooling medium entering the first outer end region from the incident channel 9 cools the first outer end region effectively while forming a pool appropriately in the first outer end region. The appropriate pool relaxes a steep temperature variation, and especially, since no valley is formed in the temperature distribution, lens effect can be corrected effectively.