An experimental study of infiltration by means of pond has been done since June in 1984 in Rokugo-alluvial fan, Akita Prefecture. Groundwater of 83 lit. per minute was intermittently supplied to a pond (area of 1.8 × 1.8 m and 1.8 m in depth). Water level in the pond attained to a height of 146 cm in late April in 1986. At this time infiltration amount is ca. 36 cm per hour. The outline is seen by reference to Figs.1-4, Table 1 and Photo 1.