In order to clarify the effect of hydrostatic pressure and added electrolyte on the sol-gel transition, the sol-gel transition of gelatin in aqueous electrolyte solution under high pressures was determined by measuring the melting temperature of the gels with a dropping ball method The concentration range of the gelatin solutions was from 9 g/L to 90 g/L, temperature range from 293 K to 313 K, and pressure range up to 500 MPa. The electrolytes used were NaCl,LiCl, and KCl at concentrations up to 1 mol/L. It was found that the gelatin gels were stabilized by pressure in the electrolyte concentration range studied, while the dependence of the electrolyte concentration on the melting temperature varied with pressure. A maximum was observed in the melting temperature versus electrolyte concentration curves at low electrolyte concentrations. For the systems containing NaCl and KCl, after passing the maximum the gel was stabilized again by the addition of the electrolyte at pressures higher than about 300 MPa. The values for the enthalpy, entropy and volume changes accompanying the gel formation were calculated from the Eldrige-Ferry’s plot and the Clausius-Clapeyron equation.