An NMR probe permits measurements to be made with its inner coil without replacing the probe. The NMR probe has three coils disposed to surround a sample tube. An inner coil can resonate with the HF and LF. An intermediate coil can resonate with the HF and LF, and produces an RF magnetic field perpendicular to the RF field produced by the inner coil. An outermost coil can resonate at least at a lock frequency. The outermost coil produces an RF magnetic field which is perpendicular to the RF field produced by the intermediate coil but which is coincident in direction with the RF field produced by the inner coil.