The calibration of a specific absorption rate probe is namely a calibration of the electric field measurement sensor in the phantom liquid of high electric loss. The standard electric field method that uses the rectangular waveguide filled with phantom liquid is widely used for the probe calibration. NICT is only institute to serve the calibration for the probe. In this text, the calibration procedure of this waveguide calibration technique is described, along with the detailed procedure, the calibration result, and the uncertainty evaluation. Moreover, this text introduces other calibration techniques.