To supply a micro quantity of fluid flow substantially without pulsation by comparing a flow signal related to flow generated by a pump, with a reference flow signal, and adjusting load to the pump according to a difference signal.

Flow 305 generated by a pump 300 is supplied to a flow sensor 310, and the flow sensor 310 generates a flow signal 315 corresponding to the flow 305. The flow signal 315 is supplied to a comparator 320 and compared with a reference flow signal 317. As a result, a difference signal 325 is generated and supplied to an adjustable loading unit 330. Load to a bearing of the pump 300 is therefore adjusted by the adjustable loading unit 330 according to the difference signal 325. With this control loop, the flow 305 generated by the pump 300 can be precisely adjusted, that is, a micro quantity of fluid flow substantially without pulsation can be supplied.