A hard carbon. A total quantity of adsorbed nitrogen under a relative pressure P/P0 of nitrogen between 10−8 and 0.035 is V1 cm3 (STP)/g and a total quantity of adsorbed nitrogen under a relative pressure P/Po of nitrogen between 0.035 and 1 is V2 cm3 (STP)/g in a nitrogen adsorption isotherm determined at a temperature of 77 K for the hard carbon. The hard carbon satisfies: V2/V1≤0.20 and 20≤V1≤150, where P represents an actual pressure of nitrogen, and P0 represents a saturated vapor pressure of nitrogen at a temperature of 77 K.