Maintenance of a flow tank is facilitated. A sub-module is provided adjacent to a main module. A board is introduced in the sub-module, and is heated by a heater that is at a heating position, is moved to the main module, solder is applied by a flow tank in parallel with insertion of a component by a component insertion device, and thereby the component is mounted. If a maintenance condition is established, introduction of boards is stopped, the heater is moved to a standby position, and the flow tank is moved to a maintenance position of the sub-module. Maintenance is performed on the flow tank and since the component insertion device is not present above the flow tank, it is possible to facilitate inspection, removal, and the like of the flow tank.