  M\"ossbauer spectroscopy is a technique employed to investigate the
microscopic properties of materials using transitions between energy levels in
the nuclei. Conventionally, in synchrotron-radiation-based M\"ossbauer
spectroscopy, the measurement window is decided by the researcher
heuristically, although this decision has a significant impact on the shape of
the measurement spectra. In this paper, we propose a method for evaluating the
precision of the spectral position by introducing Bayesian estimation. The
proposed method makes it possible to select the best measurement window by
calculating the precision of M\"ossbauer spectroscopy from the data. Based on
the results, the precision of the M\"ossbauer center shifts improved by more
than three times compared with the results achieved with the conventional
simple fitting method using the Lorentzian function.
