To provide a method of pressure sterilization capable of sterilizing object materials such as foods without impairing their quality, needing no cooling step after sterilization essential in retort sterilization and the like low in operating cost with high safety, and capable of making a sure sterilization.

This method of pressure sterilization is characterized by comprising the following practice: treatment temperature is set at a temperature somewhat lower than the biological defensive function-developing temperature of Bacillus stearothermophilus IFO 12550 spore as the indicator bacterium and the shortest treatment time is set at such a time that a liquid dispersed with an object material such as a food, which undergoes heating at the treatment temperature and pressurization under a pressure higher than a specified level, penetrates the spore coat of the Bacillus stearothermophilus and infiltrates into microbial cells, and the liquid is infiltrated into microbial cells at the treatment temperature and the above pressure for the shortest treatment time or longer followed by depressurization, and by the volume expansive force of the liquid developed at that time, the membrane tissue of the microorganisms is destructed.