  Based on the data of spectral monitoring of the yellow hypergiant V509 Cas
performed in 1996-2018 at the 6-m telescope with the spectral resolution of
R$\ge$60 000, we studied in detail its kinematic state at various levels of
extended atmosphere. No signs of presence of a companion were found. An
agreement of radial velocities measured on the permitted and forbidden
emissions of metal ions, as well as their strict temporal stability led us to
the choice of the systemic velocity of the star Vsys=$-63$ km/s. The position
of forbidden [NII] emissions forming in the circumstellar medium is strictly
stable and is systematically shifted by $-6$ km/s relative to the metal ion
emissions. A conclusion on the variation of the [NII] emission halfwidths and
intensities (the lines have become narrower and more intense) is made after the
observations in 1996 and these parameters did not vary over the next 22 years
of observations. The velocities measured from the shortwave FeII(42) absorption
components are located in a narrow interval of Vr=$-$(84$\div$87) km/s, which
indicates the stability of expansion of the upper layers of the atmosphere. The
overall atmosphere of the hypergiant is stable, excluding the layers close to
the photosphere. The velocity variability in range of Vr=$-$(52$\div$71) km/s,
identified by the positions of strong metal ion absorption cores, may be a
manifestation of pulsations in deep atmospheric layers, where this type of
lines are formed.
