We present a real-time rendering method of translucent materials with complex shape by estimating object's thickness between light source and view point precisely. Wang et al.  has already proposed a real-time rendering method treating arbitrary shapes, but it requires such huge computational costs and graphics memories that it is very difficult to implement in a practical rendering pipe-line. Inside a trans-lucent object, the energy of incident light attenuates highly depends on the object's optical thickness. Translucent Shadow Maps (TSM)  is able to compute object's thickness using depth map at light position. However, TSM is not able to calculate thickness accurately in concave objects. In this paper, we propose a novel technique to compute object's thickness precisely and as a result, we achieve a real-time rendering of translucent materials with complex shapes only by adding one render-ing pass to conventional TSM. Copyright is held by the author / owner(s).