The frequency-dependent viscosity and conductivity of polymer gel electrolytes are investigated in the megahertz region to clarify how polymer affects the ionic mobility. The electric conductivity shows no dispersion below 10 MHz, where slow dynamics of polymer are observed in shear relaxation spectra, which indicates that the ionic motion is uncorrelated with the slow dynamics of polymers that determines the steady state shear viscosity. On the other hand, the shear viscosity around 100 MHz is somewhat correlated with the direct-current (DC) molar conductivity, suggesting that the measurement of the high-frequency viscosity can be a probe of the so-called microviscosity associated with the mobility of an ion.