To provide a contract price payment system for smoothly achieving the payment of the price of a contract business without time-lag from a high rank subcontractor to a low rank subcontractor.

The contract price payment system uses a price proxy payment undertaker to mediate between a business proprietor and a contractor by using a Web site and a system management server which provides the Web site, wherein the system management server performs: contractor registration processing for registering the price proxy payment contractor and the contractor; a payment system use acceptance processing for registering and storing parties for each business, and for preparing and storing an amount of work done detailed list for a price proxy payment contractor and an amount of work done detailed statement for each contract contractor; and payment processing in each period for judging whether the contract sum and the amount of work done of business are matched between mutual parties or the amount of work done sum is within the fixed range of a business progress scheduled amount of work done sum, and for calculating a payment sum corresponding to the amount of work done amount of work done for each fixed period, and for displaying it on the amount of work done detailed list and the amount of work done detailed statement, and for making a remittance request to a bank.