To provide a method of establishing operational environment of an earth leakage circuit breaker which allows for easy determination and establishment of a normal operating environment of an earth leakage circuit breaker.

A confirmation is made whether or not the ground resistances of the ground electrode 16 of a power reception transformer 12 and the ground electrode 15 of an electric apparatus 11 satisfy a reference value, and a confirmation is made whether or not an obstacle 17 exists between the ground electrode 16 of the power reception transformer 12 and the ground electrode 15 of the electric apparatus 11. If the obstacle 17 exists, the resistance between the ground electrode 16 of the power reception transformer 12 and the ground electrode 15 of the electric apparatus 11 is measured. When the resistance between the ground electrodes 15, 16 exceeds the reference value, it is rendered to satisfy a specified value. Consequently, the resistance between the ground electrodes of the power reception transformer 12 and the electric apparatus 11 becomes almost zero, and satisfies the operating environment of an earth leakage circuit breaker 14.