The ophthalmic YAG laser system YC-1800 emits Nd: YAG laser (hereafter called “YAG laser”) pulse beam by Q-switching. The YC-1800 allows the safe and bloodless treatment of intraocular diseases for outpatients by mechanical disruption caused by energy of the YAG laser pulses. The main purposesof the YC-1800 are posterior capsulotomy for secondary cataract, iridotomy for acute angle-closure glaucoma, and for pupillary membranectomy for traction retinal detachment. The YC-1800 has a slit lamp for observation that includes the YAG laser and its controlling mechanism. The YC-1800 is also equipped with an operation panel and knobs that facilitate operation. The compact and lightweight power supply box is installed separately for lightness and compactness of the system. In addition, a motorized table for the YC-1800 is available optionally.