Reactor

A reactor, comprising:

• a plurality of divided cores having a shape obtained by dividing an annular core in a circumferential direction, the divided cores being made of a soft magnetic material;
• a core gap part disposed between the divided cores in the annular core formed by combining the plurality of divided cores, the core gap part being made of a non-magnetic material;
• an annular heat-dissipating case that houses the divided cores and the core gap part;
• and
• a coil wound around the heat-dissipating case,
• wherein,
• one end surface of the heat-dissipating case is an open end surface,
• the heat-dissipating case includes cutout portions on edges of an outer circumferential surface and an inner circumferential surface that are in contact with the open end surface,
• the coil is wound along the cutout portions, and
• the cutout portions in the heat-dissipating case are disposed distant from the core gap part so that the coil wound along the cutout portions is disposed only in a region overlapping the divided cores.