The invention relates to an isochoric pulsatory freezing process and to a device for carrying out the same, meant to be used for preserving a biological material or product, while ensuring in the intracellular and extracellular space thereof a fine structure of ice crystals. According to the process claimed by the invention, in a first step, the biological material is introduced into an isochoric chamber (1) at the ambient pressure, at higher temperature, close to freezing, said chamber being filled with an aqueous solution, while minimizing the gaseous phase between the aqueous solution and a cover (2) of the chamber (1), then the chamber is externally cooled, step during which the initiation of the crystallization and accumulation of ice inside the chamber (1) take place with the increase of the pressure and stabilization of the thermodynamic balance of phases between the ice and the aqueous solution inside the chamber (1), when the temperature decreases under the freezing point corresponding to the atmospheric pressure for the aqueous solution, after which, at a certain temperature between the freezing point at the atmospheric pressure and the temperature of the triple point between ice I, ice III and the aqueous solution within the phase diaphragm for the aqueous solution, a valve (3) is opened and puts in connection the content of chamber (1) with the ambient pressure, which creates, upon the drop of the chamber pressure, the conditions to reestablish the thermodynamical balance by the crystallization of small ice particles dispersed in the biological product, and finally, the frozen biological material having a fine structure of ice crystals in the intra and extracellular space of the treated volume is brought back to the atmospheric pressure, to the initial temperature close to the freezing point in atmospheric pressure conditions. The claimed device comprises an isochoric chamber (1) , a cover (2) provided with a valve (3) which allows the pressure within th
