The invention provides a specimen pretreatment apparatus, a specimen pretreatment cartridge, and a specimen pretreatment method, which can reduce required time of pretreatment and can deal with a large amount and a less amount of plasma. Disclosed is a specimen pretreatment apparatus comprising: a specimen container holder configured to hold a specimen container for containing a plasma specimen; a reagent container holder configured to hold a first reagent container for containing a first reagent including magnetic particles on which a nucleic acid in the plasma specimen is adsorbed; a reaction unit in which a plurality of reaction containers are disposed, the reaction unit being configured to accelerate, in each reaction container, reaction of the plasma specimen and the first reagent; a washing unit in which a washing container is disposed, the washing unit including a magnetic force applying portion configured to apply magnetic force to the washing container; a dispensing unit; and a controller programmed to control the dispensing unit to: dispense the plasma specimen contained in the specimen container and the first reagent into the plurality of reaction containers in the reaction unit; dispense a mix liquid of the plasma specimen and the first reagent from each of the plurality of reaction containers into the washing container; and remove a liquid component from the washing container while the magnetic particles contained in the discharged mix liquid is attracted by the magnetic force applying portion.