This rotor (10) for a rotating electric motor (1) includes a hollow cylindrical rotor core (20) with a plurality of laminated electromagnetic steel plates (80, 81, 82). The inner and outer circumferential surfaces of the rotor core (20) each face a magnetic gap. The rotor core (20) is interposed between a first rotating support member (30) and a second rotating support member (40). A flange (72) is formed on a first end of a tubular pin (70) protruding from a first hole (31) of the first rotating support member (30). A tubular expansion part (73) of the tubular pin (70) plastically deforms due to fluid pressure so as to come into close contact with a through hole (21) of the rotor core (20), the first hole (31) of the first rotating support member, and a second hole (41) of the second rotating support member.