Provided is a tree feeder of a forestry harvester capable of smoothly and reliably feeding a felled tree under cooperation between a mid-roller and a pair of right and left feed rollers while avoiding idle rotation of the feed rollers, even when a difference in rotational speed arises between the mid-roller and each of the feed rollers. The tree feeder of the forestry harvester comprises a hydraulic circuit in which each of a pair of right and left hydraulic motors of a pair of right and left feed rollers is hydraulically connected in series with a corresponding one of a pair of left and right hydraulic motors of a mid-roller, wherein the tree feeder is configured to rotate the mid-roller and the right and left feed rollers by the hydraulic motors thereof so as to feed a felled tree in a manner enabling delimbing, and wherein the mid-roller comprises: an inner wheel fixedly connected to respective rotary shafts of the pair of left and right hydraulic motors thereof； an outer wheel； and a ring-shaped rotation transmission member disposed between the inner wheel and the outer wheel, wherein the ring-shaped rotation transmission member is fixedly attached to an inner surface of the outer wheel or an outer surface of the inner wheel, and configured to transmit the rotation of the inner wheel to the outer wheel, and, when a difference in rotational speed arises between the mid-roller and each of the left and right feed rollers, allow the outer wheel to roll on the inner wheel in a slipping manner.
