In this paper, we propose a radiosity method for the point-sampled geometry to compute diffuse inter reflection of light. Most traditional radiosity methods subdivide the surfaces of objects into small elements such as quadrilaterals. However, the point-sampled geometry includes no explicit information about surfaces, presenting a difficulty in applying the traditional approach to the point-sampled geometry. The proposed method addresses this problem by computing the inter reflection without reconstructing any surfaces. The method realizes lighting simulations without losing the advantages of the point-sampled geometry.