The authors carried this study with woods of Quercus and other many species freshly cut down or air-dried for 1-10 months, containing various quantities of water, using the black-charcoal-kilns of “Tokita-Gama” of 2.7m long and “Hyojun-Gama” of 3.6m long. (1) Yield of charcoal by weight percentage based on water-containing wood became larger gradually, according as moisture content of the wood decreased, but moisture content had scarcely any influence on yield percentage based on absolutely dried wood. (2) Volume of charcoal obtained from unit volume of wood became larger gradually, according as moisture content decreased. (3) Volumetric gravity and hardness of charcoal became smaller gradually, according as moisture content of the wood decreased, and this tendency was especially remarkable in the case of Quercus-wood. (4) It was revealed by this experiments of black-charcoal-making, according as moisture content of wood incresed, much more firewoods were necessary, and according as moisture content of wood decreased, quality of charcoal obtained became bad. The authors sopposed the most advantageous water contents of wood in blaek-charcoal-making would be 30-35%.