At the experimental forest of Tokyo University in Prefecture Chiba, authors carried out parallel experiments with green wood and seasoned wood, respectively 3 times uncontinuously, by the plant of dry distillation of wood in a semi-industrial scale. According to the results when with the seaaoned wood, it was established that the shortening of the distilling time, higher yields of valuable products and concentration of pyroligneous acid were realized. when using the green wood, if the drying of it was sufficiently executed for a long time. the yields of charcoal, tar and acetic acid were a little increased and hardness of charcoal was remarkably enhanced.