1. A system for supporting prior evaluation of a service for improving business, comprising: input means for accepting selection of an index indicating a degree of improvement of the business and accepting setting of multiple future scenarios which influence success/failure of improvement of the business; storage means for storing the index and the multiple future scenarios; and calculation means for calculating a primary estimate value of the index for occurrence of each scenario of the multiple future scenarios and calculating a secondary estimate value based on the primary estimate value and a primary risk corresponding to the primary estimate value.