a disk drive device is disclosed including a supporting mechanism for supporting a plurality of magnetic disks , a single motor , and a transmitting mechanism . the supporting mechanism comprises a plurality of bearing mechanisms , each of which rotatably supports each of the magnetic disks , respectively . each bearing mechanisms is formed as a tube , and a rotatable shaft is connected to each disk and rotatably supported in each tubular bearing mechanism . the rotatable shaft is provided with grooves which generate a pumping effect when a fluid is passed therethrough , whereby the rotatable shaft is supported in the tubular bearing mechanism without friction therebetween . the transmitting mechanism comprises an endless belt for transmitting a rotation of the motor to the supporting mechanism .