The adoption of contra-rotating rotor has been proposed in response to a demand for the higher specific speed of axial flow pump. The internal flow field and blade rows interactions between the front and rear rotors should be considered in the design for higher performance and more stable operation. Then for more understanding of the internal flow of contra-rotating axial flow pump, the flow fields have been measured at various flow rates with Laser Doppler Velocimetry. In the present paper, measured flow fields between front and rear rotors at the design flow rate are shown and the flow behavior is discussed with the velocity vector distributions in the relative reference frames with front and rear rotors.