In a method for desulfurizing hot metal by analyzing S concentration of a sample taken out from the hot metal, the S concentration is analyzed rapidly and precisely by a method comprising a high frequency induction heating step of oxidizing the sample under a high frequency induction heating in a pure oxygen atmosphere to convert S in the hot metal to SO2 and an analysis step of analyzing SO2-containing gas generated in the high frequency induction heating step through an ultraviolet fluorescence method to quantify S concentration in the sample, whereby S concentration after the desulfurization is controlled precisely and hence fault of S concentration is prevented but also the increase of the cost due to the excessive addition of a desulfurization agent and step disruption at steel-making step are prevented.