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.