The purpose of this study is to examine the pressure pulsation in a centrifugal blower piping system with the discharge opening below the water surface. The effect of the piping shape on the pressure pulsation was studied experimentally. The pressure and the flow rate in the pipe line were measured for various parameters such as the depth of the discharge opening, the number of revolution for the blower, and the valve opening of the throttle valve. It was clarified that the behavior of the air-liquid interface affects the pressure pulsation in the pipe line. The pressure fluctuating ratio increases with increasing the depth of the discharge opening, and it has the maximum value at the specific depth. The dominant frequency in the pressure pulsation is influenced by the shape in the discharge opening.