A notion of spanning tree is utilized in many problems as an effective condition representing a set of simple path for some pair of two different nodes. But, when we make the model from some actual problem, it is hardly to obtain a feasible solution at the problem for this condition. Then, we introduce the notion of spannig pseudotree, and degree of similarity between tree and pseudotree. Moreover, we propose an example about extention of the problem where there exist the condition, solution graph is spanning tree.