The effect of noise on the selfsustained oscillator near subcritical Andronov–Hopf bifurcation is studied in numerical and fullscale experiments. Van der Pol oscillator is chosen as base model for investigation. The influence of both additive and multiplicative Gaussian white noise is considered. The regularities of evolution of the probability distribution in the selfsustained oscillator are analyzed with increase of the noise intensity for the cases of additive and parametric noise.