Provided are a solid electrolyte composition containing an inorganic solid electrolyte (A) having a conductivity of an ion of a metal belonging to Group I or II of the periodic table and a binder (B), in which the binder (B) is a polymer having at least one bond of a urethane bond, a urea bond, an amide bond, an imide bond, or an ester bond in a main chain and having a graft structure, a solid electrolyte-containing sheet and a manufacturing method therefor, an all-solid state secondary battery and a manufacturing method therefor, and a polymer having a specific hard segment and a graft structure and a non-aqueous solvent dispersion thereof.