The outermost bodies of planetary systems embedded in aplanetesimal disk migrate much faster than the other planets. Theoutward migration of such bodies is self-sustained by supplyingfresh planetesimals up to the edge of the disk. We study thedynamics of gravitational interactions between an outer planet andmassive planetesimals during this process. The investigation isbased on using our N-body symplectic integrator. It is shown thatthe efficiency of the resonant capture of planetesimals during outward planetary migration depends on many parameters of themodel. As a result of planetary migration, planetesimals canbe transferred to a region located far from the planet withoutany resonant trapping. The reversion of the planetary migration isan important element of the process studied. We show that themigration of an Earth-mass planet in the trans-Neptunianplanetesimal disk well reproduces the main orbital features of the“cold” Kuiper belt population.