An NMR apparatus is provided, which is capable of being used for mass spectrometry and structure determination of a gas sample. The NMR apparatus includes: a sample vaporization unit 1 having a sample vaporization chamber 1a; an ionization unit 2 having a ionization chamber 2a and connected to one end of the sample vaporization unit 1 so that the ionization chamber 2a communicates with the sample vaporization chamber 1a; a long-length pipe 3 connected to one end of the ionization unit 2 so that the inside of the pipe 3 communicates with the ionization chamber 2a; a cooling unit 4 having a cooling chamber 4a and connected to one end of the long-length pipe 3 so that the cooling chamber 4a communicates with the inside of the long-length pipe 3; a superconducting magnet 5 having a tubular portion 5a into which the long-length pipe 3 is inserted, the superconducting magnet 5 being capable of applying a magnetic field and a gradient magnetic field in the axial direction of the long-length pipe 3; an ion guide 6 which decelerates gas ions; a mass analysis unit 7 which is used for mass screening of gas ions; and a nuclear magnetic force amplification unit 8 which amplifies the nuclear magnetic force of gas ions.