Provided are a solid electrolyte composition containing a sulfide-based inorganic solid electrolyte, an active material having a surface coated with an oxide having an ion conductivity, and a dispersion medium, in which the dispersion medium includes a specific polar dispersion medium, a solid electrolyte-containing sheet having a layer containing a sulfide-based inorganic solid electrolyte, an active material having a surface coated with an oxide having an ion conductivity, and a specific polar dispersion medium, an all-solid state secondary battery, and methods for manufacturing a solid electrolyte-containing sheet and an all-solid state secondary battery.