There is provided a board work system which can improve production efficiency by optimizing a mounting order of components on a circuit board. An electronic component mounting machine is provided with a tape-type supply device and a wafer-type supply device. In a case where an error rate which shows the number of defective dies included in the wafer provided in the wafer-type supply device is input by a user, an integrated control device uses the input value in processing (step S3). In addition, in a case where the error rate is not input by the user, the integrated control device decides a value obtained by averaging the number of defective dies of the same type of wafer in production information as the error rate (step S5). In addition, the system decides the mounting order of mounting the components of the tape-type supply device or the wafer-type supply device on the circuit board based on the decided error rate, or changes the mounting order after the decision.
