To provide an inexpensive impeller having excellent durability.

The impeller 1 is composed of a boss member 2 having a shaft fitting hole 22a to which a rotating shaft is fitted, and a plurality of blades 3 equally disposed in all directions on the periphery of the boss member 2. Of the boss member 2 and the blades 3, at least the blades 3 are structured by either one of three-phase precipitation hardening high silicon stainless steel made from a mixed structure of martensite, austenite, and ferrite, or two-phase precipitation hardening high silicon stainless steel made from a mixed structure of austenite and ferrite. The boss member 2 and the impellers 3 are joined by welding.