PROBLEM TO BE SOLVED: To provide a voltage measuring device for an electric fence and a voltage monitoring system for an electric fence using the same for preventing invasions of wild animals and escapes of livestock by an electric fence and for monitoring behavior of animals and monitoring maintenance of the electric fence by monitoring a voltage of an electric wire of the electric fence.SOLUTION: A voltage measuring device 2 for an electric fence for measuring a voltage of an electric wire W in an electric fence F includes: a voltage measuring part 5 for measuring a voltage in a prescribed position of the electric wire W a radio communication part 6 having a communication function by a wireless LAN and a transmission control part 7 which makes the radio communication part 6 transmit a measured voltage and measured time when the voltage measured by the voltage measuring part 5 is a prescribed voltage or lower and makes the radio communication part 6 transmit a measured voltage and measured time when the measured voltage subsequently recovers to the prescribed voltage or higher.
