CONNECTION DEVICE AND COMMUNICATION SYSTEM

PROBLEM TO BE SOLVED: To provide a connection device and communication system capable of sharing information between a communication network related to power line communication for superposing a signal such as a communication signal on a power supply line and a communication network related to inband communication for superposing a signal such as a communication signal on a control line for transmitting a control signal such as a control pilot signal, when a power supply device charges a power storage device mounted on a vehicle.SOLUTION: There is provided a connection device 24 comprises: a coupling transformer 247 having a first primary coil 247a for connecting with a communication network related to power line communication for transmitting a communication signal through a pair of feeder lines 31 and 32 as a medium, a second primary coil 247b for connecting with a communication network related to inband communication for transmitting a communication signal through a control line 33 and ground line 34 as a medium, and a secondary coil 247c electromagnetically coupled to the first primary coil 247a and second primary coil 247b; and a relay unit 246 connected to the secondary coil 247c of the coupling transformer 247.