A method of manufacturing an integrated impeller has a first shroud forming a bottom portion, a second shroud forming a lid portion, a hub formed at the center portion of the first shroud, and blades that section a flow path which is formed between the first shroud and the second shroud and through which a fluid flows. This method includes forming a flow path on the inner circumferential side of the impeller; and forming a flow path on the outer circumferential side of the impeller. The step of forming the flow path on the outer circumferential side of the impeller has the steps of: while rotating the linear electrode having a tip-end part and a base-end part about a longitudinal direction axis thereof, applying electric discharge machining to the first shroud; applying electric discharge machining to the second shroud; and applying electric discharge machining to the blade.

A method of manufacturing an integrated impeller has a first shroud forming a bottom portion, a second shroud forming a lid portion, a hub formed at the center portion of the first shroud, and blades that section a flow path which is formed between the first shroud and the second shroud and through which a fluid flows. This method has the steps of: forming a flow path on the inner circumferential side of the impeller; and forming a flow path on the outer circumferential side of the impeller. The step of forming the flow path on the outer circumferential side of the impeller has the steps of: while rotating the linear electrode having a tip-end part and a base-end part about a longitudinal direction axis thereof, applying electric discharge machining to the first shroud; applying electric discharge machining to the second shroud; and applying electric discharge machining to the blade.