A fan unit comprises an electric rotary machine (e.g. electric motor) having a rotor and a fin structure unified with the rotor. The fan unit further comprises a rotation mechanism for rotating the rotor. The rotor is formed to have an opening at a central portion thereof in a direction along which the opening permits fluid to flow. The fin structure is coupled with a peripheral portion of the opening so as to be unified with the rotor. The peripheral portion incorporates the rotation mechanism therein.