Abstract: Diluting dosage device, in which there is a dilution-liquid cylinder (20), a sample cylinder (30), a press knob (2), and a blocking valve (21). When the knob is depressed, the blocking valve is closed and the pistons (16 and 15) in the cylinders move rearwards, whereat dilution liquid flows into the dilution-liquid duct (2), and a certain quantity of sample into the sample duct (23). When the press knob is returned, the blocking valve is opened and the pistons push the sucked sample and a certain quantity of the dilution liquid out through the tip (7).