Disclosed is a method of manufacturing an all-solid state battery. The method includes coating a first slurry or composition having on a substrate to form a first electrolyte layer a predetermined thickness, coating a second slurry or composition on the first electrolyte layer to form a second electrolyte layer having a predetermined thickness, laminating an electrode layer on the second electrolyte layer, bonding the electrode layer to the second electrolyte layer through pressing, and removing the substrate from the first electrolyte layer. The first slurry or composition of the first electrolyte layer has content of a binder less than that of the second slurry or composition of the second electrolyte layer, and thus, the substrate may be easily removed from the first electrolyte layer.