The formation of laccase by 12 strains of Botrytis cinerea, which are isolated from vineyards in Yamanashi Prefecture, is studied. The production of laccase was influenced by the strains and the culture media. The culture of B. cinerea with grape juice showed higher activity of laccase than that cultured in potato-dextrose medium, and the cultivation in potato-dextrase medium with the addition of phenolic compounds and copper salt increased laccase activity.