Abstract: An information processing system to implement reverse auction for a price list is disclosed. The system includes a price list storage unit storing an individual transaction value when a supplier performs transaction under a reference transaction condition as a price list of a supplier, a requirement storage unit storing a tentative number of transaction times used in the reverse auction in association with the reference transaction condition; and a reverse auction unit performing the reverse auction where a bidder is a supplier and a bid price is a total amount of individual transaction values when assuming to perform the tentative number of times of transactions under each reference transaction condition with reference to the price list storage unit and the requirement storage unit.

Abstract: A bidding system in accordance with the present invention receives bids from bidders by disclosing call-for-bid information that has been received from a bid caller calling for bids, and receives information about a winning bidder determined by the bid caller based on that bidding information. The bidding system includes a bidding processing portion 14 receiving bidding price range information sent by a bidder over a communication network, and a fee charge processing portion 13 for calculating a fee based on the bidding price range information received by the bidding processing portion 14. Furthermore, shared keys are used in order not to divulge information to the site operator.