A device for observation of the NMR signal in the Earth field is described. This device provides information about the macroscopic motion of liquid due to the interaction of the magnetic nucleus moments of the moving liquid with the external magnetic field. The operation principle of the device measuring the flowrate of the liquid in study is based on detection of phase changes in the NMR signal (nucleus free induction decay) in the geomagnetic field. The theoretical possibility of flowrate measurement by the NMR signal in a homogeneous magnetic field has been proved experimentally.