To make the size of wood chips very fine while maintaining the cutting capability at a practically useful level and also make the chip size uniform even when the wood quality of a cut tree and the condition of the wood fiber are not uniform.

This tree cutting device 1 comprises an intake 2, a conveyance part 3, a housing 4, a first cutting part 5, a second cutting part 6, a fan 7, a drive shaft part 8 and a discharge part 9. The second cutting part 6 is made up of shredder discs 61, 62, partitions 63, shredder knife support shafts 64, a set of four shredder knives 65a-65d and a set of four partition walls 66a-66f arranged in such a manner that these walls embrace the tip parts of the shredder knives 65a-65d of the partitions 63 in a non-contact fashion. Wood chips produced by cutting using the first cutting part 5 are further cut to the finer size.