“Laser”, the amplification of the light by stimulated emission, was experimentally observed in ruby for the first time in 1961. Within the short space of ten years, a distinct branch of physics and technology has developed from it， which is called “Quantum Electronics”. The paper describes the review of the investigations and the applications on ruby laser. The reports on laser applications have an increasing tendency even years than the analysises on laser systems in present. Ruby laser is simularly as well. Especially, the development of the applications to plasma and technology, and the material science have been amazed.

Ⅰ 序論　Ⅱ Ruby Laserの特性　Ⅱ-1 緩和発振　Ⅱ-2　Ⅱ-3 Mode選択　Ⅱ-4 連続発振　Ⅲ Ruby Laserの応用　Ⅳ 結論