When the accelerated protons hit the solar surface, high-energy gamma-rays and neutrons are produced. However observed intensity of gamma-rays and neutrons at the Earth depends on not only the position of the flare on the solar surface but also the direction of the accerelated protons and helium ions. Without precise knowledge of the angular distribution of secondary particles, we cannot estimate correct intensity of accelerated ions. Therefore we have made a Monte Carlo simulation based on the GEANT 4 program to understand the angular distribution induced by the proton-solar atmosphere and the helium-solar atomosphere collisions.