Batch type carbonizer subjects to direct loading of materials to be treated. The carbonizing process is to heat up the materials under non oxygen condition by heating panel of the jacket circumferentially composed in the shell, in which hot air at a high temperature supplied from Hot Air Generator. After finish treatment in 40 to 60 minutes, a hot air circulating inside the jacket, is automatically converted into cool air to lower the temperature of carbonized product down to level of safety handling. The cooled product is discharged outside automatically by outlet conveyor.