Dynamical behavior of the one minute resolution Polar Cap (PC) index was studied by using the 1995--2000 data sets. It was found that the probability distribution functions (PDFs) of the PC-index increments display a strong non-Gaussian shape in both positive and negative time intervals, depending on the time of an increment. This indicates that PC-index is not characterized by a global time self-similarity but rather exhibits an intermittency, previously detected in solar wind and auroral electrojet index time series. The PDFs for the PC index increments are fitted by the functional form proposed by Castaing et al. <1990> to describe intermittency phenomena in an ordinary turbulent fluid flow. The parameters that characterize the PC index increments PDF are very close to those reported before for solar wind magnetic field probability distribution functions. This indicates that the PC index adequately reflects the solar wind effects on the high-latitude magnetosphere.