A sulfur-carbon composite in which sulfur is combined with porous carbon is provided. In the sulfur-carbon composite, a mass loss ratio X at 500° C. in thermal mass analysis and a mass ratio Y of sulfur/(sulfur+carbon) in an observation visual field at a magnification of 1000 in SEM-EDS quantitative analysis satisfy the relationship of |X/Y−1|≤0.12, and porous carbon has a mean pore diameter of 1 to 6 nm, and a specific surface area of 2000 m2g−1 or more and 3000 m2g−1 or less.