The RF-field structures are measured by the magnetic probe arrays in the edge region of the central cell of the Hanbit magnetic mirror device. The probe data was obtained during RF discharges produced by a slot antenna with frequency of 3.75 MHz and heating power of up to 150kW. For further reliable measurements, the calibration of the probe was carried out with a network analyzer for the RF frequency range of 1 – 10 MHz. The experimental results from the measurements are presented.