A manufacturing system which can restrain the margin of a semiconductor integrated circuit. The integrated circuit including a fixed circuit unit and a reconfigurable circuit unit outputs, to a configuration determining server, an operation time which was calculated by a detecting unit and a calculating unit. The configuration determining server, by using the operation time obtained from the integrated circuit, calculates performance data which indicates the characteristics of the fixed circuit unit, selects, based on the performance data, a piece of configuration information indicating a circuit configuration that is optimum for the processing of the reconfigurable circuit unit, and outputs the selected piece of configuration information. The integrated circuit builds a circuit in the reconfigurable circuit unit in accordance with the output piece of configuration information.