It is proved that a two-dimensional magnetized plasma in equilibrium cannot exist in a negative temperature state. The displacement of a test particle in the two-dimensional magnetized plasma is described in terms of a two-dimensional Langevin equation, i.e., a two-dimensional harmonic oscillator subject to a stochastic electric field, and it is found that the mean dispersion of displacement of the test particle in the two-dimensional magnetized plasma has a rapid spreading process which comes from the statistically non-stationary stochastic force, is proportional to the cubic power of time and is independent of the magnetic field.