As methods of seasoning of wood, four methods were compared: (1) roasting method as usual in the case of retort, (2) adopting of roasting and simultaneous heating of wood with the hot gas generated by the charcoal gas producer, (3) simple direct heatig of wood with the hot gas generated by the charcoal gas producer, and (4) adopting of roasting and simultaneous direct heating of wood with the hot exhausted gas from the .fire-place. According to the result, the most excellent one was the fourth. By this method, convection of air in the retort being promoted, much of moisture was rapidly carried off and the special fuel was unnecessary.