It is well known that the slow mass-movement due to ground frost is the most important process in alpine regions. Though there are a lot of studies about it, the detail of process is remained without any complete explanation. The slope processes must be complicated, because the climatic environment of the Japanese high mountains is peculiar, with the severe influences of strong prevailing wind, dense snowfall during winter and heavy rainfall during summer. In this paper the natures and rates of slow mass-movement processes were investigated on the vegetation-free and debris-mantled slopes above the forest line of Mt. Shirouma Dake (36°4, 5'N, 137°45'E), the Japan Alps.<br> The five localities for field investigation were selected on the slopes with gradient between 10° and 30° at the altitude of about 2, 500m a, s.1. All slopes are covered with the surfacee rubble layers consisting of rhyolite rock fragments without fine matrix, while two of them are free from snowcover even in winter because of strong wind, the others are coverd with :snowpatches remaining till summer. Surface rock fragments were painted on twenty-two measurement lines nearly horizontal to the slopes in 1974, and fourteen pieces of plastic tubes were inserted into the ground vertically in 1970 and 1974. The deformations of painted lines were measured in the summer of 1975 and 1976, and those of the plastic tubes in the summer of 1976.<br> The deformation features of painted lines are classified into a parallel pattern (Fig. 4-A) and four kinds of lobe like patterns, that is, a narrow festoon (Fig. 4-B), a festoon (Fig. 4C), a wedge (Fig. 4-D), and a scattered pattern (Fig. 4-E). The factors controlling the :nature of the movement were considered analyzing the observations of the slope materials, the slope gradient, the type and intensity of ground frost, and the condition of soil moisture on each pattern of deformation, respectively.<br> The parallel pattern occurred on all slopes mantled with the thick surface rubbles of cobble size. The rate of the movement was low, ranging 1_??_10 cm/yr. These imply that the processes forming this pattern are talus creep and frost creep. Since the tops of plastic tubes showed mostly the same feature of the movement as that of the parallel pattern, talus creep and frost creep should have occurred on all of the studied slopes.<br> On the other hand, lobe like patterns were recognized on the slopes with the thin surface rubbles of pebble size. The narrow festoon pattern which occurred on snowless gentle slopes with sorted stripes is considered to have been mainly formed by downslope displacement of particles due to the daily repetition of making-up and collapse of needle ice (needle ice creep). The festoon and wedge patterns which ocurred on the snow-rich slopes with thin surface rubbles of pebble size were formed by gelifluction and rapid solifluction in the snow-melting season. The scattered pattern was found not only on the slopes with or without thin surface rubble layers in snow-rich environment, but also on steep slopes in snowless environment. Slope-wash by rain and melting water acts on important role in the movement of rock fragments on the former and rapid rolling down of particles does on the latter, respectively.<br> The high rate of the movement occured in the place where many processes overlap with each other. The rate largely depends upon not only the climatic condition but the property of slope materials.