The snowfall on the Japanese high mountains is supplied by the winter monsoon wind from the Japan Sea. The environmental change of the Japan Sea during the Last Glacial Age, caused by the lowering of sea level, would have certainly affected the amount of snowfall which nourished mountain glaciers in Japan. The purpose of this paper is to reconstruct the amount of snowfall during the Last Glacial Age by the glacial landforms, in order to evaluate the amount of the lowering of sea level.Major glacial advances during the Last Glacial Age in the Japanese high mountains occurred in the two glacial periods which is separated by an interstade around 30, 000y.B.P. The glacial extension and the paleoclimate of each glacial period, reconstructed from glacial, periglacial and fluvial landforms, are as follows (Fig. 1):1) Period about 60, 000-40, 000y.B.P.: Glaciation attained to its maximum extension. Lowering of summer temperature and the southern shift of polar front could be referred. The drop of the amount of snowfall which was not so great as in the younger period, would suggest the inflow of the Tsushima Current into the Japan Sea.2) Period about 25, 000-10, 000y.B.P.: In spite of the lower air temperature, the glacial extension was much more limited than in the former period. The amount of snowfall should have decreased the most, reflecting on the drop of surface water temperature of the Japan Sea, in which the Tsushima Current ceased to enter in this period, because of the lowering of sea level.The amount of snowfall is reconstructed by using the glacial landforms at Mt. Kurobegoro (2, 840m) in the Northern Japanese Alps. At first, the extension and the shape of a cirque glacier (named Kurobegoro Glacier) at the stage II (ca. 25, 000y.B.P.) is reconstructed, based on the topography of lateral moraines of this stage (Figs. 2 & 3).Then, the mean air temperature during the ablation season on the Kurobegoro Glacier is calculated from the estimated air temperature at Toyama in the Last Glacial Age (Tab. 1), by using the decreasing rate of air temperature of 0, 6°C/100m (Tab. 2). The total ablation of each altitude on the glacier is calculated by the formula (1), and finally, the net accumulation (ablation) on the glacier, by the formula (5).The result of the calculation (Tab. 3) shows that the mass balance of the Kurobegoro Glacier was realized when the degree-day factor (f) is between 0, 3 and 0, 8. The probable decrease of the value of f during the Last Glacial Age leads to the conclusion that the amount of snowfall at this stage should have been less than 50-70% of the actual value. The estimation of the amount of the lowering of sea level which caused this diminution of the amount of snowfall will be an interesting subject of studies in future.