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.