The present invention provides a radio node apparatus, a multi-hop radio system and a multi-hop radio system constructing method, capable of constructing a tree type multi-hop radio system in which mutual radio nodes determine a radio node which becomes a root node of a tree in an autonomous manner and the root node is set as a root in an autonomous manner. The radio node apparatus includes a storage unit for storing state information, used for constructing a multi-hop radio system, including information for specifying a root radio node apparatus positioned at a summit of the multi-hop radio system, with the radio node apparatus has a connection, and the number of hops from the root ratio node apparatus, a collection unit for collecting state information transmitted from surrounding radio node apparatus, and a selection unit for selecting a host connection-accepting radio node apparatus on the basis of the information for specifying the root radio node apparatus and the number of hops included in the collected state information.