Asama volcano erupted on September 1, 2004, and volcanic bombs, lapilli, and volcanic ash were ejected, The distribution of the volcanic bombs was investigated by using IKONOS high-resolution satellite imagery. IKONOS imagery with one-meter ground resolution enabled us to identify the distribution of the impact craters greater than three meters in diameter. Many impact craters are distributed northwestward, according to the distribution density chart of the impact craters. The crater shape of Asama volcano was analyzed by using DEM created from airborne laser scanner data, and the result shows that there is no obstruction in the crater area to prevent volcanic bombs to be projected at an angle of 63 degree that gives the maximum attainment distance (Iguchi et al., 1983). It suggests that the shape of the crater did not affect the distribution pattern of the impact craters. The outline of the eruption can be understood based on the distribution pattern of the impact craters larger than three meters in diameter, which can be interpreted from IKONOS imagery.