Liquid phase static relative permittivities epsilon(r) of water + acetone and water + dimethyl sulfoxide have been measured over the whole mole-fraction range under pressures up to 300 MPa at 298.15 K. The pressure P dependence of epsilon(r) values for each mixture was well fitted to the Tait-type equation, and the Tait-type parameters, A and B, were determined. For each aqueous mixture, the composition dependence of (partial derivative ln epsilon(r)/partial derivative P)(T) values at 0.1 MPa evaluated from the static relative permittivity at 0.1 MPa, epsilon(r)(0.1), and the Tait-type parameters was compared with that of the isothermal compressibility kappa(T) at 0.1 MPa. Values of epsilon(r)(-2)(partial derivative epsilon(r)/partial derivative P)(T) at 0.1 MPa as a function of composition were also compared for both aqueous mixtures. For pure acetone, (partial derivative ln epsilon(r)/partial derivative P)(T) and epsilon(r)(-2)(partial derivative epsilon(r)/partial derivative P)(T) values at 0.1 MPa were correlated with temperature by a combination of the present values and the ones evaluated from the literature epsilon(r) data.