An impeller is formed of two parts, i.e., an inner peripheral side part and an outer peripheral side part. The inner peripheral side part is molded in a cylindrical shape. The outer peripheral side part is formed by integrally molding an annular disc externally fitted to an outer peripheral surface of the inner peripheral side part, a plurality of blades provided at an interval in a circumferential direction on a surface that faces the other side in the axis line direction of the annular disc and forming a flow path extending in a radial direction, and a cover covering the plurality of blades from the other side in the axis line direction and having an insertion hole to which the inner peripheral side part is inserted in the axis line direction at an interval in a radial direction.