In an apparatus which applies periodic pulsation to a solution flowing through a conduit while undergoing perfusion by a pump, a first valve is disposed in the conduit downstream of the pump, a bypass line is provided to the conduit downstream of the first valve, and a second valve is disposed in the bypass line for withdrawing some of a first pulsed flow formed in the conduit by opening and closing the first valve, through the bypass line as a second pulsed flow. A valve driving circuit periodically opens and closes the first valve and second valve at predetermined time schedules so that the second pulsed flow is superimposed upon the first pulsed flow to form a waveform in the conduit. Any desired pulsatile waveform can be obtained by adjusting the pulse width, the crest values, the delay time, etc., of the two pulsed flows.