Provided is a reactor configured to suppress damage to a core thereof accompanying vibrations during an operation of the reactor and to reduce noise, while fixing an assembly of a coil and the core to a casing. A reactor includes: a coil, a magnetic core and a coil, a casing and a sealing resin portion. The reactor includes a support portion that is attached to the casing and arranged so as to overlap an upper face of an outer core portion of the magnetic core exposed from the coil, and, together with the sealing resin portion, prevents detachment of the assembly from the casing, the sealing resin portion is interposed between an upper face of the outer core portion and a lower face of the support portion, and the outer core portion and the support portion are not in direct contact with each other.