In this contribution dynamics of quantum oscillator under external impulse force is investigated. The oscillator with symmetric polynomial potential in the well of impenetrable walls is considered. The potential consists of quadratic and cubic terms; the cubic term depends on modulus of coordinate. Influence of walls and anharmonicity on vibrations is discussed. Properties and peculiarities of resonances have been studied in context of non-stationary Schrödinger's equation at specified initial conditions. Solutions for the probability density, expectation coordinate as function of time; Fourier's spectra were analyzed in detail.