An energy monitor for electron beams has been developed which makes use of the elastic scattering of electrons caused by a foil placed in the beam path. The scattered electrons are magnetically analyzed and detected by measuring the direct current from a plastic scintillator. During use of the beam the sweep of the magnetic field is repeated automatically, and the energy spectrum is displayed on a storage oscilloscope. Performance of the monitor constructed for a 15 MeV linear electron accelerator is presented.