PURPOSE: To enable discharge to be monitored with high reliability by providing a fluorescent discharge collector in the vicinity of a discharge gap, and further providing an optical fiber for transmitting output from the collector and a detector circuit to generate an indication signal based upon the judgement that discharge is taking place.

CONSTITUTION: The fluorescent output end of a fluorescent discharge collector 11 is optically connected to an optical fiber 14 via an optical connector 13, and an output signal from the collector 11 is transmitted to a monitor place via the fiber 14. A fluorescent output signal 20 is converted into an electrical signal E in the ODE conversion section of a detector circuit 15 and amplified by a signal amplification section 17. Thereafter, the output signal 20 is inputted to a detection section 18 having a threshold value. When an electrical signal Ed exceeding the threshold value is detected, the detection section 18 judges discharge as occurring in a discharge gap on a steel tower, and sends a signal for instructing a display section 19 to make reporting. According to this construction, information can be displayed, regarding a steel tower having the collector 11, a discharging arrester, the accumulated discharge frequency of the arrester or the like, and the behavior of the discharge gap can be detected even in the daytime, thereby improving the reliability of a discharge monitor device.