We give sufficient conditions for ergodicity of the Markovian semigroups associated to Dirichlet forms on standard forms of von Neumann algebras constructed by the method proposed in Refs. [Par1,Par2]. We apply our result to show that the diffusion type Markovian semigroups for quantum spin systems are ergodic in the region of high temperatures where the uniqueness of the KMS-state holds.Keywords : Standard forms of von Neumann Algebras; Dirichlet forms; Markovian semigroups; ergodicity; quantum spin systems; KMS-states.Markovian semigroup associated to (E, D(E)). Let N be the fixed point space of T t ;T t is ergodic if and only if M is a factor. We apply our result to the translation invariant Markovian semigroups for quantum spin systems [Par1], and show that the semigroups are ergodic in region of high temperatures where the uniqueness of the KMS-state holds. Let us describe the background of this study briefly. The need to construct Markovian semigroups on von Neumann algebras, which are (KMS) symmetric with respect to non-tracial states, is clear for various applications to open systems[Dav], quantum statistical mechanics[BR] and quantum probability[Acc, Part]. Although on the abstract level we have quite well-developed theory[Cip1, GL1, GL2], the progress in concrete applications is relatively slow. For construction of Dirichlet forms and associated Markovian semigroups, we refer to [BKP1, BKP2, MZ1, MZ2, Par1, Zeg] and the references there in. During the last ten years, systematic methods to construct Dirichlet forms and associated Markovian semigroups of jump and diffusion types have been developed. Nontrivial translation invariant symmetric semigroups of jump type for quantum spin systems have been constructed and the strong ergodicity of the semigroups has been established in Refs. [MZ1, MZ2]. See also [Zeg] and the references there in. In [Par1], we gave a general construction method of Dirichlet forms of diffusion type in the framework of the general theory of Dirichlet forms and Markovian semigroups on standard forms of von Neumann algebras developed by Cipriani[Cip1].The method has been used successfully to construct Dirichlet forms and associated Markovian semigroups for quantum spin systems [Par1], CCR and CAR algebras with respect to quasi-free states[BKP1, BKP2, KP], and quantum mechanical