The present invention provides a kineti energy-electric energy conversion device for waterpower device or pump which is mounted easily with higher assembling precision. When assembling the waterpower device (1), after holding a rotor (8), a stator (7) as well as a drum-shaped sealing component (5) and setting them between an inlet side tube (21) and an outlet side tube (22), tabling drum-shaped connecting component (6) from the inlet side to ensure a stop projecting part of the drum-shaped connecting component (6) to hitch a annular entablature of the inlet side tube (21), then bending the outlet side end of the drum-shaped connecting component (6) towards inner side, so as to form annular a warp part. The result is that the inlet side tube (21) and the outlet side tube (22) are linked bythe drum-shaped connecting component (6) when holding the rotor (8), the stator (7) as well as the drum-shaped sealing component (5) between whereout.