In medical, scientific, and other fields, transparent surface visualization is useful for investigating inner three-dimensional (3D) structures. Such visualization typically involves the use of polygon graphics in which the polygons must be sorted along the line of sight. However, sorting involves considerable computation time for large-scale data. Furthermore, the order of polygons in the sorting can often become indefinite, especially for intersecting surfaces. Therefore, particle-based volume rendering that does not require sorting is proposed as a transparent-rendering method. The proposed method obtains slice images with non-uniform opacity using color and opacity maps similar to volume rendering. The method initially generates the particles, a process it performs only once. It additionally employs particle shuffling, which requires considerably less computation time than particle sorting. To demonstrate the efficacy of the proposed method, we rendered 3D-fused images, including slice–slice and volume–slice images, for medical volumetric data. The results show that the performance of the proposed method is satisfactory in cases in which the area of the particle is greater than that of the cell.