In a power network system (10A), a plurality of power routers including at least a first power router (100A) and a second power router (100B) are connected through respective input/output terminal parts in a multi-stage configuration. A predetermined amount of power is transmitted to the input/output terminal part of the power transmission destination (230A) through a first input/output terminal part (210A), the input/output terminal part of the second power transmission source (220A), and the DC bus (201A) in the second power router. The power network system includes as power information about power in the input/output terminal part of the power transmission destination, identification information of the first power transmission source (110A), and an intermediate measurement value of power received in the first input/output terminal part in a predetermined time period.