PROBLEM TO BE SOLVED: To provide, on an impeller divided into upper and lower members and having a magnet installed between both the members, a joint structure capable of surely adhering both the members by a simple manufacturing process.SOLUTION: The inner peripheral end of a part of a plurality of vanes 6 of the impeller 22 is connected to a rotating shaft 7, and the outer peripheral end of each vane is connected to an annular connecting portion 23. A plurality of driven magnets 12 are installed between the annular connecting portion and the impeller lower member 25 to form a magnetic coupling with a drive magnet installed on a rotor. An inner positioning projection 28 which contacts the driven magnets from the inside is provided on the reverse surface of the annular connecting portion with a predetermined space from the inner periphery, and an outer positioning projection 30 to the driven magnets is provided within an annular recess 26 formed by an outer circumferential wall 25a and an inner circumferential wall 25b provided respectively on the outer and inner peripheries of the impeller lower member. The annular connecting portion is bonded to the impeller lower member by an adhesive 27 filled in an area where the upper ends of the outer circumferential wall and inner circumferential wall of the impeller lower member contact the annular connecting portion.
