In a work system for substrates which includes plural working machines conveying circuit substrates through two paths and in which the circuit substrates are conveyed through the two paths from the working machine disposed upstream out of the plural working machines to the working machine disposed downstream, a circuit substrate of which the work result is not good is conveyed to the downstream working machine earlier than the circuit substrate of which the work result is good in a state in which the circuit substrate of which the work result is good and the circuit substrate of which the work result is not good are able to be conveyed to the downstream working machine by the upstream working machine.