A method for producing an LGPS-type solid electrolyte can be provided, the method includes preparing a homogeneous solution by mixing and reacting Li2S and P2S5 in an organic solution such that the molar ratio of Li2S/P2S5 is 1.0-1.85; forming a precipitate by adding, to the homogeneous solution, at least one MS2 (M is selected from the group consisting of Ge, Si, and Sn) and Li2S and then mixing; obtaining a precursor by removing the organic solution from the precipitate; and obtaining the LGPS-type solid electrolyte by heating the precursor at 200-700° C.