A method for re-arrangement of a group resource of an M2M device arranged according to a hierarchical tree structure is disclosed in accordance with one embodiment of the present invention. The method is performed by a first M2M device which owns a first group resource, and the method comprises the steps of: receiving, from a second M2M device, a specific request message for the first group resource; determining whether it is necessary to transfer at least one member of the first group resource as a member of a group resource of another M2M device; determining, in order to transfer the at least one member as a member of the group resource of the another M2M device, whether to use a group resource existing in the another M2M device or whether to generate a new group resource in the another M2M device; and if a new group resource is generated in the another M2M device, adding the at least one member as a member of the new group resource, wherein the first group resource is added as a member of the new group resource if the another M2M device is higher than the first M2M device in the hierarchical tree structure, and the new group resource is added as a member of the first group resource if the another M2M device is lower than the first M2M device in the hierarchical tree structure.