The stability of the electret state in polylactide films with a white soot dispersed filler has been studied using the method of thermally stimulated relaxation of the surface potential. The best electret properties were shown to exhibit by the films with a filler content of at least 4%, and the films polarized in a negative corona discharge field. The parameter values of the relaxation processes (the activation energy value and effective frequency factor one) responsible for the electret state of this material were found by numerical simulation. The relaxation time of the electret state at room temperature was determined for the samples under study. The obtained results allow us to recommend the composites as an active packaging material.