Ninety-eight stomach contents of the Japanese Ptarmigan, Lagopus mustus japonicus, obtained in Japan Alps during 1926-28 and owned by Mr. Jicho Ishizawa, were kindly offered to the author for food analysis. The analyses were made by month (March to November) and individual. Twenty-five plant (13 other species, reported by other authors, were not found) and eleven animal items were identified. Animal foods are taken during July and August only by young and the females accompanied by them. Vaccinium leaves and fruits occurred in the highest frequency, next the leaves of Empetrum, and other several species are favoured, but their % frequency changed by season. The needles of Pinus pumila was not so important quantitatively (though occurred in high frequency), and according to Ishizawa, its fruits are mostly consumed by Nutcracker but about 10% are left and fall on the snow which are eaten by the ptarmigan.