We devised a simple "pumping" method to make gelatin sponge particles for transcatheter arterial embolization. As the frequency of pumping increased, the number of particles 0.2-1.6 mm in diameter increased, whereas no particles of more than 3.2 mm in diameter were present after 20 pumpings. After passing through the microcatheter, particles of less than 0.2 mm in diameter were relatively increased by about 10 points in both the pumping and cutting methods. It was histologically demonstrated that the size of embolized arteries corresponded well to the size of particles. These results suggest that our "pumping" method offers sufficient quality for transcatheter arterial embolization.