Connector for electrical connection includes coupler, cable, switch mechanism, failure detector and transmitter. Coupler is removably inserted in and connected to reception side connector provided in machine which is equipped with storage battery. Cable includes two or more electric wires including power line configured to be electrically connected to reception side connector via coupler. Cable is connected to device that performs at least one of supplying power to machine and receiving power from machine. Switch mechanism opens and closes electrical circuit between coupler and power line. Failure detector detects occurrence of failure of coupler. Transmitter transmits detection result of failure detector to device through at least one first electric wire of the two or more electric wires. Switch mechanism opens and closes the electrical circuit in accordance with control signal transmitted through first electric wire.