To provide a relay apparatus and a relay method by which an app can be flexibly connected to a device and various apps can be connected to various devices to realize stable operation. The invention is a relay method for mediating a connection between an app and a device, and the relay method includes: when an input specification of data required for an app whose use is to be started is input, comparing an output specification held by each processing node provided in an existing data processing path with a data item included in the input specification; connecting an output of the data processing path to the app whose use is to be started if the existing processing node and the existing data processing path are able to satisfy the input specification; adding a new processing node and comparing an output specification of the new processing node with the input specification if the existing data processing path is not able to satisfy the input specification; and connecting an output of the new processing node to the app whose use is to be started if the new processing node is able to satisfy the input specification.