A radiation information management device comprises: a measuring unit (41) that measures unwanted radio wave radiation radiated from a balanced transmission line (50); a comparing unit (42) that compares a measured value of unwanted radio wave radiation; and a management information generating unit (43) that refers a comparison result and generates the management information related to the unwanted radio wave radiation. The management information generating unit (43) notifies to communication devices (100), (200), which take a measure to reduce transmitting power based on the management information regarding the unwanted radio wave radiation. In the communication devices (100), (200), the unwanted radio wave radiation radiated from the balanced transmission line can be controlled within the reference value.