Curtain treatment with white reflection sheets at the veraison stage was applied to the wine grape 'Cabernet Sauvignon'. Compared with mulch treatment and the control, hanging sheets on both sides of the main stem of the grape tree significantly increased the coloration of the berries and wine and the anthocyanin content in the grape skins. Yeast-assimilable amino acid in the juice in curtain-treated grapes was significantly decreased compared with that in the control. Curtain treatment with white reflection sheets improved the color of red wine grapes.