PURPOSE: To enable stable work without loosing weight balance of an excavator even if a user changes the interval between excavation shafts.

CONSTITUTION: In a multishaft excavator, which excavates a plurality of holes at the same time with a plurality of excavation shafts 8 juxtaposed, a gear box to mount a plurality of drive motors is fixed to the driver 4 being supported freely in ascent and descent by the leader 2 of the excavator. The output shaft 14 of each drive motor is supported rotatably in this gear box, and also gears are fixed and those gears are coupled with each other at the junction by gear. The output shaft 14 and a driven shaft 33 are supported in parallel within the bearing box 12 supported rotatably at the bottom of the bear box, and both shafts are coupled with each other by gear. And, it is made possible to fix the bearing box 12, at the position of rotation, to the driver 4, and the excavation shaft is connected to the driven shaft 14.