PURPOSE: To obtain a device for nuclear magnetic resonance capable of receiving and transmitting resonance signals with high sensitivity and a high signal-to-noise ratio by forming an alternating magnetic field composed of an uniform magnetic field which is small in the absolute value of intensity during the period of time for irradiation against a high frequency magnetic field, and of an uniform magnetic field which is great in the absolute value of intensity during the period of time for receiving resonance signals.

CONSTITUTION: An uniform alternating magnetic wave form 10 is composed of a high frequency magnetic field irradiating section 11, of an ascending section 12 wherein an uniform alternating magnetic field intensity is increased, of a high frequency signal receiving section 13 receiving resonance signals, and of a descending section 14 wherein the descending section 14 is connected with the high frequency magnetic field irradiating section on the side where the sign from the ascending section 12 is opposite, the repeat of which situation forms an alternating magnetic field wave form 10 allows the wave form to alternate repeatedly between plus and minus in turn. The uniform alternating magnetic wave 10 as described above can be generated by sending alternating current having the wave form same as the uniform alternating magnetic field wave form 10 into an uniform magnetic field coil 1. In the high frequency magnetic field irradiating section 11, a high frequency magnetic field is generated within an uniform magnetic field space 8 by sending high frequency pulses 2 with a specified frequency as high frequency current into a high frequency coil 5 for the specified period of time.