A magnetically stabilized fluidized bed nuclear fission reactor (MSFBR) concept is proposed. A large number of fuel particles with 1 mm diameter containing ferromagnetic material are floated in the reactor core by balancing the gravitational force and the drag force of helium coolant flow. Superconducting solenoid coils produce magnetic fields inside the reactor core. Advantages of the MSFBR concept are its excellent heat transfer property from the fuel to the coolant and improved safety, while the bed is stabilized by the magnetic force, contrary to previous fluidized bed reactor concepts.