A solid electrolyte and a method of manufacturing the same are provided. The solid electrolyte contains x atomic % of lithium, y atomic % of phosphorus, z atomic % of sulfur, and w atomic % of oxygen, in whichthe x, the y, the z, and the w satisfy the following expressions (1)-(5): 20≦x≦45   (1) 10≦y≦20   (2) 35≦z≦60   (3) 1≦w≦10   (4) x+y+z+w=100   (5), and apexes of X-ray diffraction peaks in an X-ray diffraction pattern obtained by an X-ray diffraction method using a Kα-ray of Cu exist at diffraction angles 2θ of 16.7°±0.25°, 20.4°±0.25°, 23.8°±0.25°, 25.9°, 0.25°, 29.4°±0.25°, 30.4°±0.25°, 31.7°±0.25°, 33.5°±0.25°, 41.5°±0.25°, 43.7°±0.25°, and 51.2°±0.25°, respectively, in the X-ray diffraction pattern, and a half-width of each of the X-ray diffraction peaks is not larger than 0.5°.