To provide a nitrogen monoxide production inhibitor for preventing or improving complexion deterioration caused by nitrogen monoxide production and a skin care preparation that contains the nitrogen monoxide production inhibitor and is suitable for improving complexion.

The nitrogen monoxide production inhibitor comprises a pyrroloquinoline quinone derivative represented by general formula (1) [wherein R1, R2 and R3 are each independently a short-chain-length alkyl group, alkenyl group, aralkyl group, alaryl group, phenyl group or a hydrogen atom] and/or its pharmacologically acceptable salt as an active ingredient.