A retrieval device according to the present embodiment associates one tag key with one node and removes a node not having a tag key when a trie tree generating unit generates a trie tree. Moreover, because a tag key having a low priority is registered in a node close to a root node when the trie tree generating unit registers tag keys in the nodes of the trie tree, the retrieval device can narrow down a node region that is a comparison target when a trie tree searching unit performs a retrieval process.