  We present the surface magnetic field conditions of the brightest pulsating
RV Tauri star, R Sct. Our investigation is based on the longest
spectropolarimetric survey ever performed on this variable star. The analysis
of high resolution spectra and circular polarization data give sharp
information on the dynamics of the atmosphere and the surface magnetism,
respectively. Our analysis shows that surface magnetic field can be detected at
different phases along a pulsating cycle, and that it may be related to the
presence of a radiative shock wave periodically emerging out of the photosphere
and propagating throughout the stellar atmosphere.
