PURPOSE: To set and change spaces among four circular saws according to respective lumbers as an optional value instantly by adjusting freely the positions of two outside circular saws and two inside circular positions respectively and separately by cylinders.

CONSTITUTION: Respective saw shaft frames 4 are moved instantly in the inner and outer directions by a first cylinder 3, and as respective hollow shafts 7 are installed on a saw shaft frame 4, the positions of respective outside cylinder saws 18 installed on the inside ends of respective hollow shafts 7 are adjusted instantly in the inner and outer directions. Also, respective inner shafts 13 installed on respective shaft frames 4 are moved instantly in the inner and outer directions separately by a second cylinder 16, and the positions of respective inside circular saws 19 installed on the inside ends of respective inner shafts 13 are adjusted instantly and separately between two outside circular saws 18. The intervals among the four circular saws are also set instantly. As the hollow shafts 7 are rotated by a motor 9 moving together with the saw flames 4, and the inner shafts 13 are unable to rotate separately from the hollow shafts 7, the hollow shafts 7 and the inner shaft 13 are rotated integrally by the motor 9.