To accumulate sticks efficiently to be a wood composite material having uniform strength.

Stick units U in which sticks nearly equal in length are arranged in the width direction in parallel in the longitudinal direction are transported in turn on a carry-in conveyer 11 in the longitudinal direction of each stick. The units U which are carried out in turn from the transportation side end part the conveyer 11 are mounted in turn on the pellets P of a stick unit charging mechanism 13. Each pallet P, after the stick units U being mounted, is slid horizontally to drop the units U downward. The stick units U dropped from from the pallets P are mounted on the upstream side end part in the transportation direction in an accumulating conveyer 12 to be transported.