A loading mechanism holds at least one extracting cartridge provided with a filter member, at least one waste liquid vessel for accommodating a discharged liquid of a sample liquid and a discharged liquid of a washing liquid, which discharged liquids have been discharged from the extracting cartridge, and at least one recovery vessel for accommodating a recovery liquid, which contains a recovered nucleic acid and has been discharged from the extracting cartridge. A pressurized air supplying mechanism introduces pressurized air into the extracting cartridge. A liquid injecting mechanism injects each of the washing liquid and the recovery liquid into the extracting cartridge.