The invention, which relates to a miniaturizable plasma thruster, consists of: —igniting the plasma by microhollow cathode discharge close to the outlet and inside the means for injecting the propellant gas, said injection means being magnetic and comprising a tip at the downstream end thereof; —bringing the electrons of the magnetized plasma into gyromagnetic rotation, at the outlet end of said injection means; —sustaining the plasma by means of Electron Cyclotron Resonance (ECR), said injection means being metal and being used as an antenna for electromagnetic (EM) emission, the volume of ECR plasma at the outlet of said injection means being used as a resonant cavity of the EM wave; —accelerating the plasma in a magnetic nozzle by diamagnetic force, the ejected plasma being electrically neutral.