PURPOSE: To enable rapid detection and transmission of the failure of a pantograph even in an unstable strong electric field environment by installing an optical fiber along the current collecting shoe and framework of the pantograph.

CONSTITUTION: A pantograph 1 has a current collecting shoe 2 and a framework 3. Optical fibers 4 are arranged along the shoe 2 and the framework 3. Light information is flowed from a light transmitter 6 through the fiber 4 at the operating time. When the fibers 4 are broken due to the damage of the pantograph 1, the information is interrupted, which is immediately detected by a photodetector 7, which thus transmits a signal to a controller 8. A vacuum breaker 9 and the solenoid valve of an emergency dropping device 10 are operated by a command from the controller 8, and the position of the damage is indicated on a monitor 11.