Reactor

A reactor comprising:

• a pair of yoke portion cores composed of ferrite cores and arranged opposing each other,
• one or more winding portion cores disposed between opposite planes of said yoke portion cores, each of the one or more winding portion cores having opposing end surfaces, and
• one or more coils each wound around a corresponding one of the one or more winding portion cores,
• wherein:
• one or more flange-like members are each disposed at an end part of a corresponding one of the winding portion cores in a way of being externally connected with a periphery of said corresponding one of the one or more winding portion cores, each of said one or more flange-like members being a separate element from the corresponding winding portion core and having an outer surface,
• each of said one or more winding portion cores is composed of a soft magnetic metal core,
• each one of the opposing end surfaces of the one or more winding portion cores is in the same plane as the outer surface of one of the one or more flange-like members, and
• each of said one or more flange-like members is a homogenous steel plate in which a notch from an inner peripheral end to an outer peripheral end is provided at one place in a peripheral direction.