A reactor apparatus for a continuous depolymerization of polymers, in particular polyolefins from polymer wastes, includes a primary reactor, further includes a heating unit for a heating and a melting and for an at least partial depolymerization of the polymers within the primary reactor, and includes at least one primary circulation unit for a circulation of molten polymers in the primary reactor, wherein the reactor apparatus comprises a secondary reactor, which is connected downstream of the primary reactor and forms a reactor cascade with the primary reactor.