A polycarbodiimide composition which is obtained by carbodiimidizing a reaction product of a linear aliphatic diisocyanate and an alcohol, and which is configured such that: the alcohol contains a polyol and a monool; the molar ratio of the hydroxyl groups derived from the polyol to the hydroxyl groups derived from the monool in the alcohol, namely (hydroxyl groups derived from polyol)/(hydroxyl groups derived from monool) is less than 2.0; and the carbodiimide equivalent of this polycarbodiimide composition is 300 g/mol or more but less than 550 g/mol.