A disk unit, comprising a first pivot shaft for supporting vertically oscillatingly a holding arm which holds a second turn table so that the second turn table for supporting a second disk not stored in a cartridge and transmitting a rotating force to the second disk can be installed on and removed from the first turn table for supporting a first disk and transmitting a rotating force to the first disk and a second pivot shaft for supporting the holding arm so that it can be rotated and moved away horizontally, the height dimension and depth dimension of the device capable of being reduced.
