The invention provides a reactor to be built in a power converter. In the reactor, an induction component composed of a coil being a winding of a conductor wire, a core in which interior a magnetic path is formed and an insulation bobbin positioning and engaging a wire wound part of the coil is housed in a case to be soaked with a mold resin. Inner bottom face of the case has a plurality of surfaces having not less than two different heights letting the outside bottom of the case a reference surface, and the lower end face of the core is in contact with any of the case inner bottom surfaces excluding the lowest inner bottom surface. As a result, the reactor is suitable for on-vehicle applications to achieve reduced article variation as well as a longer service life, a shorter operation time and decreased cost.