PURPOSE: To optimize the natural frequency of a propeller driveshaft in the form of a tubular shaft for each specific kind of vehicle.

CONSTITUTION: Tubular shaft propeller driveshafts 6, 8, 10 are formed having a central tubular axis range Rm and end members 11, 12 at each end. The shafts 6, 8, 10 have additional masses 13, which are formed to decrease in inside diameter Di and to increase in outside diameter Da and which are arranged axially symmetrically or asymmetrically. By devising the arrangement of the additional masses 13, the mass centers of gravity of the shafts 6, 8, 10 are displaced to enable adjustments of their natural frequencies to thereby optimize the natural frequency of each shaft for each specific kind of vehicle.