In a component supply unit arrangement determination method for a mounter, in which multiple component supply units are exchangeably arranged and which mounts a component on a board based on a job, as the component supply unit to be exchanged for the component supply unit to be newly arranged due to switching of multiple jobs whose execution order is determined, the component supply unit is selected such that a time interval from a job, in which the component supply unit is to be used last, to the switching is long, among the component supply units that are arranged before the switching and are not planned to be used in a job after the switching. In addition, an arrangement position of the selected component supply unit is determined as an arrangement position of the component supply unit to be newly arranged.