Abstract: A pipette device adapted to removably mount a tip at its lower end and having a housing in which there are provided a cylinder chamber communicating with the interior of the mounted tip, a plunger adapted to operate in the cylinder chamber for sucking a liquid and then discharging the same, a direct current motor coupled to the plunger through a plunger driving mechanism, and a potentiometer for producing a voltage signal representing the position of the plunger, so that sucking and discharging of the liquid can be effected by detecting the voltage signal produced by the potentiometer and controlling the direction and amount of the rotation of the motor by the utilization of such detected voltage signal. Also disclosed is a control device for use with the pipette device including a servo system for receiving the voltage signal produced by the potentiometer as a feedback signal and a sequence circuit adapted to change the balance-point of the servo system in a preselected sequence.