The present invention is a spectroscopic analyzer that when measuring the concentration of a predetermined component contained in sample gas in a reduced pressure state lower than atmospheric pressure, obtains the concentration of the predetermined component with accuracy. The spectroscopic analyzer is one that measures the absorbance of the predetermined component contained in the sample gas in a reduced pressure state lower than atmospheric pressure, and calculates the concentration of the predetermined component with use of a calibration curve indicating the relationship between the absorbance of the predetermined component and the concentration of the predetermined component and a relational expression between the pressure of the sample gas at the time of the measurement and the concentration of the predetermined component. In addition, in a graph with one axis as pressure axis and the other axis as concentration axis, the relational expression has an intersection point other than zero with the pressure axis.