A mechanism which can easily acquire a connection relationship of each device even in a multilayered network system having a plurality of protocols is provided. A network system has at least one network including a master processing unit and one or a plurality of slave processing units. Each of first, second, and third devices holds characteristic information indicating whether or not the device has a master processing unit or a slave processing unit. The first device includes a network management unit that acquires single-layer network configuration information from each master processing unit included in the network system to generate multilayer network configuration information indicating a connection relationship of each device in the network system.