Reactor and manufacturing method for reactor

A reactor comprising:

• a coil;
• and
• a magnetic core that includes a plurality of core pieces and a plurality of gap members, the coil wound around the magnetic core, each of the plurality of core pieces having a pair of core-insertion projection portions, each of the core-insertion projection portions having a recession portion disposed on an outer peripheral surface of the respective core-insertion portions, the plurality of gap members interposed between at least one set of the core pieces, the magnetic core forming a closed magnetic circuit when the coil becomes excited,
• wherein a constituent material of the core pieces is a composite material containing a soft magnetic powder in an amount of 30 volume percent to 70 volume percent inclusive, a remaining portion being a non-metallic inorganic material in an amount of 20 volume percent or less and a resin, and
• one of the at least one gap members includes a resin foam, the resin foam having a plurality of air bubbles and contacts the core pieces and the coil so as to reduce a vibration applied to the reactor, an unfoamed resin sheet seated within the recession portion of the respective core-insertion projection portions.