A production management system of a component mounting line configured from multiple component mounters arranged in a line on a conveyance path along which a circuit board is conveyed, wherein in each component mounter components supplied from a component supply device are picked up by a suction nozzle and mounted on the circuit board , the production management system comprising: a production management computer connected to the multiple component mounters via a network such that communication is possible between the production management computer and the multiple component mounters , wherein a board ID recording section , on which is recorded or memorized a board ID, which is board identification information, is provided on the circuit board conveyed in the component mounting line , the multiple component mounters are configured to identify the board ID of the circuit board that is loaded during production and send the board ID to the production management computer , measure actual machine data for early-stage-discovery of a mounting defect at a specified measurement interval during production, and send a measurement result of the measuring to the production management computer , and the production management computer is configured to save the board ID with a time stamp sent from the multiple component mounters for each of the multiple component mounters , monitor whether there is possibility of a mounting defect based on the measurement result of the actual machine data for early-stage-discovery of a mounting defect for each of the multiple component mounters , and when determining that there is a possibility of a mounting defect at any of the component mounters , extract the board IDs of the circuit boards on which components were mounted at the component mounter since a previous time the measurement of the actual machine data for early-stage-discovery of a mounting defect at the specified measurement interval was performed, based on the measurement interval and the board ID with time stamp, and display a list of the extracted circuit boards as a list of circuit boards for which there is a possibility of a mounting defect. a production management computer connected to the multiple component mounters via a network such that communication is possible between the production management computer and the multiple component mounters , wherein a board ID recording section , on which is recorded or memorized a board ID, which is board identification information, is provided on the circuit board conveyed in the component mounting line , the multiple component mounters are configured to identify the board ID of the circuit board that is loaded during production and send the board ID to the production management computer , measure actual machine data for early-stage-discovery of a mounting defect at a specified measurement interval during production, and send a measurement result of the measuring to the production management computer , and the production management computer is configured to save the board ID with a time stamp sent from the multiple component mounters for each of the multiple component mounters , monitor whether there is possibility of a mounting defect based on the measurement result of the actual machine data for early-stage-discovery of a mounting defect for each of the multiple component mounters , and when determining that there is a possibility of a mounting defect at any of the component mounters , extract the board IDs of the circuit boards on which components were mounted at the component mounter since a previous time the measurement of the actual machine data for early-stage-discovery of a mounting defect at the specified measurement interval was performed, based on the measurement interval and the board ID with time stamp, and display a list of the extracted circuit boards as a list of circuit boards for which there is a possibility of a mounting defect. <EOS>