In recent years, there are anonymous routing protocols for mobile ad-hoc networks. These protocols provide anonymous communication between an arbitrary pair of nodes. However, there are also some multipoint-to-point sensor networks. In those environments, we have to consider all routes not between an arbitrary pair of sensor nodes but between an arbitrary one sender node and a specific destination node. These existing protocols consider to only security, so nodes may not be able to work efficiency in those environments. In this paper, we propose a new anonymous routing protocol for such multipoint-to-point sensor networks based on efficient routing protocols and existing anonymous routing mechanisms. Moreover, we evidence superiority of our proposal by comparing the amount of information for anonymous routing and a time for route establishment with that of existing protocols. We show that our protocol can establish the anonymous route faster than existing ones and reduce the information for routing from existing ones.