As the energy use from woody biomass is increased woody biomass supply from softwood logs only may not be sufficient. The necessity of cutting hardwood trees such as oak is now increasing because of an increase in the damage caused by Japanese oak wilt. Therefore, it is anticipated that the use of hardwood as woody biomass will increase. However, it is difficult to construct an efficient supply system because few data are available on the harvesting and transportation of hardwood materials. In this study, hardwood branches with low carrying efficiency were chipped to reduce the volume, and its rate of volume reduction and the chipping productivity was measured. We found that the chipping productivity was 5.5 t-dry/hour (9.7 t-wet/hour, 30.4 chip-m<sup>3</sup>/hour) with a 60 mm hole screen, 3.6 t-dry/hour (6.2 t-wet/hour, 18.4 chip-m<sup>3</sup>/hour) with a 40 mm hole screen, and 3.0 t-dry/hour (5.2 t-wet/hour, 14.9 chip-m<sup>3</sup>/hour) with a 25 mm hole screen. The bulk density of the branches of the hardwood tree is 0.08 t-dry/m<sup>3</sup>, and after chipping, it became 0.19 t-dry/m<sup>3</sup>, and the rate of volume reduction was 41%.
