A minimum cQst spanning tree game is called ultrametric if the cost function on the edges of the underlying network is an ultrametric. We show that every ultrametric mlnimum cc/st, spanning tree game is reduced to a cost allocation game on a rooted tree. It follows that there exist･ O(n2) time algorithms for computing the Shapley value, the nucleolus and the egalitarian allocation of the ultrametric minimum cost spanning tree games, where n is the number of players.