Full endoscopic spinal surgery(FESS)is the the least invasive surgery among the current spinal surgeries. FESS approach can be used to perform discectomy, decompression for stenosis, posterolateral fusion, etc. with little destruction of the spinal structure and posterior supporting elements, under local or general anesthesia. A major difference from conventional spinal surgeries is “underwater surgery,” in which surgery is performed under continuous saline irrigation. In addition, for neurosurgeons, there is a steep learning curve to becoming proficient in using a small diameter endoscope for full-endoscopic surgery as well as performing treatment with the surgical field completely. We would like to explain the indication and surgical procedure of the transforaminal approach, then introduce decompression by FESS at the cervical spine level as well as full endoscopic lateral lumbar interbody fusion(ELIF).