A three-phase reactor includes an outer peripheral iron core for surrounding the outer periphery of the three-phase reactor, and at least three iron core coils, which are in contact with or coupled to the inner surface of the outer peripheral iron core. The at least three iron core coils includes iron cores and coils wound around the iron cores. Gaps, which can be magnetically coupled, are each formed between two adjacent ones of the iron cores. The three-phase reactor further includes a vibration suppressing structure part disposed in the vicinity of the gaps so as to reduce vibrations occurring at the gaps.