The invention relates to gas-discharge electrical instrumentation technology. The device for measuring electromagnetic field intensity comprises a measuring instrument for recording the glow of a gas discharge and a gas-discharge chamber that is formed between electrodes 1 and 2 separated by a dielectric 3. The electrode 1 is cylindrical, while the electrode 2 is in the form of a disk. The electrodes 1 and 2 are coupled to an electrical voltage source, wherein a capacitive element in the form of a pair comprising an antenna 5 and a connection to ground 6 is incorporated into the line coupling the cylindrical electrode 1 to the electrical voltage source. A capacitor 7 with variable capacitance is incorporated into the line coupling the cylindrical electrode 1 to the antenna 5. The technical result consists in providing the possibility of detecting a useful signal in a wide frequency range.