Reactor

A reactor in which two first cores made of lamination and I-shaped and two second cores made of lamination and I-shaped are disposed such that the two first cores are parallel to each other, the two second cores are parallel to each other and that the two second cores having respective coils therearound are perpendicular to the two first cores, thereby forming a rectangular shape, characterized in that there are provided a first spacer and a second spacer integrated with a terminal block, which are molded of insulating resin, disposed parallel to each other with the two first cores set apart from each other so as to sandwich the two second cores, have on their respective outward side faces two protrusions for positioning each first core and two other protrusions for holding longer sides of each first core with one thereof having at its tip end an engaging mechanism to secure each first core, and which have on their respective inward side faces four protrusions for positioning two neighboring corners of the respective second cores and an elevated portion provided between the four protrusions and elevated in a direction perpendicular to the length of the first cores.