A liquid chromatograph-direct coupled mass spectrometer, which comprises a liquid chromatograph section, a mass spectrometer section and an interface section coupling the liquid chromatograph section with the mass spectrometer section, the interface section being provided with a first nebulizing means for nebulizing an eluate of a hydrophobic solvent containing a sample in solution introduced from the liquid chromatograph section through a capillary continuously into a vacuum or atmospheric pressure region and the first nebulizing means being further provided with a second nebulizing means for nebulizing a hydrophilic solvent and with a heating means for heating the first and second nebulizing means has a high separability and has no limit to selection of a mobile phase solvent and an ionization solvent.