Two-dimensional particle-in-cell simulations in an acceleration area were conducted to improve thrust performance of an electrodeless-electromagnetic propulsion using a rotating magnetic field (RMF) and a magnetic nozzle. In investigation of RMF parameters dependence, we found that ohm's law between Ez and Jz does not hold in the experimental conditions. The phase difference between Ez and Jz causes a contraction motion in the plasma and degrades the thrust when Bω is strong and f is high. We also found that Bmz is harmful for the thrust generation and there is an optimum value of Bmr via investigation of magnetic-nozzle-parameters dependence. The optimum Bmr, which is numerically and theoretically obtained, is the same strong as Bω; however, the particle acceleration is insufficient in the experiments because Bmr is ten times stronger than Bω. The RMF thruster has potential for obtaining the higher thrust performance if the parameters of the magnetic nozzle are adequately selected.