To examine the effect of the surface areas of wooden block to its combustion performance, combustion tests were done with some cylindrical-shaped blocks that bored holes. Results were as follows. 1. Some blocks were naturally extinguished the fire after heating of the given time, while others were burnt out with fire flame. Difference of the burning behavior of the wooden block seems to depend on the number of bored holes. 2. When the surface area of a bored wooden block exceeded about 1.3 times the surface area of the former block, it burned out with the flame after heating of the given time. 3. The amount of a mass decrease of the block by combustion had a high positive correlation with the surface area per unit volume of the block.