Abstract: A tube rack of a centrifugal separator, in which a bottom rubber portion can be readily mounted and readily replaced, and yet such bottom rubber portion cannot be easily separated. The tube rack includes a holder (14) including a plurality of tube holes (12) each configured to accommodate a tube that is used for a sample and each includes an opening at one end portion of the holder serving as a tube insertion side, and an opening at a bottom portion of the holder that is at the other end. The tube rack includes a bottom rubber portion (15) including a plurality of bottom rubber members (25) each fits in the tube hole (12), and including connecting pieces (24). The tube rack includes a base (13) formed in a cylindrical shape having a bottom configured to accommodate and detachably hold the holder (14) and the bottom rubber portion (15), and to be inserted into a bucket of the centrifugal separator.