Beats Fujitsu by 20GB and 1,400rpm.
Toshiba has developed a 2.5in hard disk that packs in 320GB of storage, breaking Fujitsu's previous record of 300GB.
The MK3252GSX drive uses two 160GB platters and an 8MB buffer to create its 320GB of storage.
Fujitsu had held the record for laptop drive storage with the 300GB drive unveiled in July, which is due to ship later this year.
However, the Toshiba drive, due for release in November, runs faster than its Fujitsu rival. The MK3252GSX runs at 5,600rpm, while Toshiba's spins at 4,200rpm.
Fujitsu could reclaim its title by a huge margin if it successfully mass produces its promised 1.2TB laptop hard drives.
The proposed laptop drives use an improved platter design that features one-dimensionally aligned alumina nano-hole patterns with 25nm pitch.