As a thoracoscopic treatment for spontaneous pneumothorax, electrocautery has been mainly used. But contact type electrocautery has a risk of perforation of blebs. We adopted carbon monoxide laser (wave length 5.4 microns) and good coagulation shrinkage of blebs could be obtained by non-contact irradiation. CO laser was delivered by As-S glass fiber and power of fiber tip was 2-4 W. Compared with Nd-YAG laser (wavelength 1.06 microns), CO laser showed lower risk of perforation of blebs. Thoracoscopic CO laser coagulation shrinkage of blebs proved to be a important method of treatment for patient of spontaneous pneumothorax.