A contracting method and system are arranged to obtain description data in which a description content presented by one of the concerned parties with a contract to the other is built or data for specifying the description content before the concerned parties make an electronic contract for provision of a commodity or service (contract data creation signing process), generate contract data containing the description data or the specifying data (contract data creation signing process), and writing an electronic signature of both or either of the concerned parties with the contract data (contract data creation singing process and contract data signing process).