To provide an electronic transaction system which implements various selling methods by providing a notarizing means which mediates for negotiation of a price, etc.

A vendor inputs a request to register an article to a vendor terminal 13. The vendor terminal 13 prompts the vendor to input information on the article name, a price corresponding to a purchase quantity, etc., in response and registers the information in the notarizing means 15. A purchaser inputs a request to purchase an article to a purchaser terminal 11. The purchaser terminal 11 obtains and displays information on registered articles from the notarizing means 15 in response. The purchaser determines the desired article to be purchased and inputs its purchase quantity. The purchaser terminal 11 displays the price corresponding to the inputted purchase quantity. The user determines the purchase by looking at the displayed price and selects, for example, an order button. In response to this selection, the purchaser terminal 11 sends information on the transaction such as the article name, purchase quantity, and price to the notarizing means 15. The notarizing means 15 sends a request for settlement to a settlement means 17.