The article studies stability conditions for self-synchronization of vibration exciters in antiphase oscillation regime of working tools of an apparatus for granular materials processing. The apparatus operating regime provides grinding, attrition and mixing processing of material grains combined with a transportation process. The condition of stable antiphase rotation regime of vibration exciters’ rotors has been found with implementation of integral criterion of stability of synchronous motions. The condition of stable self-synchronization rotation regime of vibrational exciters’ rotors was found with the usage of integral criterion of stability of synchronous movements. The obtained relationships allow one to choose parameters of apparatus construction and to specify vibrational working tool’s operating regimes that perform effective implementation of process of granular material treatment.