Laser microprobe mass spectrometry (LAMMS) was used in a state analysis of nonmetallic inclusions and precipitates in a high purity steel. At the same time, SEM-EDX and XPS were applied for morphological, elemental, and state analyses, respectively. As an example of a pure steel sample, Ti-added ultra low carbon steel (interstitial free steel: IF steel) was selected for the analysis. Inclusions in IF steel were prepared by an acid extraction method for oxide analysis, an electron beam melting method for in situ analysis, and non aqueous solvent selective potentiostatic electrolytic etching method for in situ analysis on the electrolyzed surface for oxide and nitride. LAMMS analysis detected Ti oxide and Zr oxide as trace elements in addition to alumina which was determined as a main component of inclusions by EDX analysis, and, it was clear that each oxide existed independently. LAMMS analysis of TiN gave only a spectrum of Ti oxide related peaks but not of Ti nitride, while Ti existed as nitride thermodynamically and analytically by XPS. Hence, in LAMMS analysis, careful interpretation of spectra is needed for such inclusions as nitride, which does not show its specific spectra.