A sustained release sheet that includes a drug for treating nerve injury, wherein the sheet is applied to a nerve injury site, can maintain a high concentration of the drug over a long period, and promotes nerve regeneration without stimulating the nerves, even when the sheet is implanted in the periphery of the nerve injury site. Also provided is a production method for the sheet. This sustained drug release sheet for treating nerve injury is a sheet including a non-woven fabric that is formed from nanofibers each containing a drug such as vitamin B12 and a biocompatible polymer such as a biodegradable aliphatic polyester, and is implanted in the periphery of the nerve injury site to promote nerve regeneration.