When a status of communication between a first transmission module and a second transmission module that is located downstream of the first transmission module on a predetermined transmission path is output, received signal strength information is output for each piece of send target information in order of transmission, and regarding this output, an interval between output of received signal strength information associated with send target information transmitted immediately before transmission of one piece of send target information and output of received signal strength information associated with the one piece of send target information corresponds to a transmission period of the one piece of send target information from the first transmission module to the second transmission module. This makes it easy to grasp a status of communication between arbitrary transmission modules in a network in which information is transmitted sequentially via a plurality of transmission modules along a predetermined transmission path.