Compression neuropathy can take place when the sciatic nerves come out from the sciatic notch and they are pressed by the nearby structure while traveling to their terminus. The common causes are the pyriformis syndrome that is caused by spasm of the pyrifomis muscle, lesions around the nerves and pressures from outside the spine. It has been occasionally reported that an intraneural ganglion develops within the sciatic nerve and this causes sciatic nerve compression. However, it has never been reported that the ganglion that developed around the nerves caused sciatic nerve compression. This case is about a 49-year-old man who underwent surgery due to the ganglion around the sciatic nerves, which had been found via a magnetic resonance image.