Provided is a method for manufacturing a sintered body for an electrolyte and an electrolyte for a fuel cell using the same. More particularly, the following disclosure relates to a method for preparing an electrolyte having a firm thin film layer by using a sintered body having controlled sintering characteristics, and application of the electrolyte to a solid oxide fuel cell. It is possible to control the sintering characteristics of a sintered body through a simple method, such as controlling the amounts of crude particles and nanoparticles. In addition, an electrode using the obtained sintered body having controlled sintering characteristics is effective for forming a firm thin film layer. Further, such an electrolyte having a firm thin film layer formed thereon inhibits combustion of fuel with oxygen when it is applied to a fuel cell, and thus shows significantly effective for improving the quality of a cell.