To provide a waste liquid vessel for a nucleic acid extractor meeting with a number of extraction cartridges and free from contamination trouble.

The waste liquid vessel 3 is composed of a vessel body 14 and a partition frame 15 detachably attached to the upper part of the vessel body 14. The partition frame 15 has partition plates 18 assembled in a lattice form. The lower face 18a of the partition plate 18 is positioned below the lower end of a lower nozzle 2c of an inserted extraction cartridge 2 and above the liquid level of the discharged liquid. Pressurized air is blasted from the lower nozzle 2c immediately after passing and discharging the whole injected specimen liquid through a filter 2a. Since the air is let out through a region under the partition plate 18, it is not blown fiercely against the liquid surface of the discharged liquid to prevent the generation of contamination.