An electromagnetic transceiver apparatus for a NMR apparatus has an intermediate frequency generator for preparing an intermediate wave, a transmission frequency converter for preparing, on the basis of an intermediate frequency of the intermediate wave, an electromagnetic wave to be radiated from a transmitter coil, a reception frequency converter for processing a signal received by the NMR probe, an analog-digital converter for converting an output of the reception frequency converter into a digital signal, an IQ detector for performing detection on the basis of an output of the analog-digital converter, a phase locked loop and a switch inserted between the analog-digital converter and the reception frequency converter to select either an input from the intermediate frequency generator or an input from the reception frequency converter.