Abstract: The electrolyte sheet for solid oxide fuel cell of the present invention has different surface roughnesses between the peripheral region and the region other than the peripheral region at least on one side. The surface roughness Ra(b) in the peripheral region is at least 0.05 ?m and less than 0.3 ?m. The surface roughness Ra(i) in the region other than the peripheral region is at least 0.2 ?m and at most 1.2 ?m. And, the ratio of Ra(i) to Ra(b) (Ra(i)/Ra(b)) is more than 1 and at most 4. Here, the surface roughness Ra(b) and the surface roughness Ra(i) are arithmetic mean roughness values and determined by an optical and laser-based non-contact three-dimensional profile measuring device in accordance with a German standard ‘DIN-4768’.