Control of electron energy and electric field in a low‐pressure argon plasma produced by a hybrid (2.45 GHz microwave and 13.56 MHz rf) discharge was studied for thin‐film preparation. The hybrid plasma was found to be useful over a wide range of magnetic field strengths, unlike conventional microwave plasma. A novel probe measurement revealed that the electron temperature and density were effectively controllable by the microwave power and the magnetic field strength, rather than the rf power, and the potential profile describing the electric field was controllable by the magnetic field strength. The control of an ion beam injected from the microwave into the rf plasma is described.