This paper discusses multicast routing in ad hoc networks. In multicast routing, a node delivers the same message to the other nodes within a multicast group along with a multicast tree. Since nodes are moving around in ad hoc networks, the links between the nodes change frequently. However, the multicast tree must be maintained to deliver the messages regardless of the link changes. This paper gives a description of an autonomous clustering-based hierarchical multicast routing protocol in ad hoc networks. Since the autonomous clustering scheme is adaptive to the node movement, the proposed multicast routing can maintain the multicast tree in despite of link changes. This paper shows the effectiveness of autonomous clustering-based hierarchical multicast routing from the point of view of adaptability to link changes and scalability to multicast members.