We examined high‐frequency spectral decay characteristics of ground motions for inland crustal earthquakes in Japan, which are important in strong ground motion predictions. We examined 105 earthquakes ( 3.3–7.1), including seven large earthquakes ( 5.9–7.1). Spectral decay characteristics were accurately evaluated assuming the ‐squared source model and using two approaches: the model (commonly used in Japan), described by the cutoff frequency and the power coefficient of spectral decay , and the model (commonly used in worldwide), the exponential spectral decay model, described by the parameter and the specific frequency at which a spectrum starts to decrease linearly with increasing frequency in log–linear space. For large earthquakes, we estimated to range from 6.5 to 9.9 Hz and from 0.78 to 1.60 in the model, and to range from 0.014 to 0.051 s and from 2 to 4.5 Hz in the model. In both approaches, we found that the spectral decay characteristics are regionally dependent. in the model and in the model tended to be smaller for large earthquakes than for moderate and small earthquakes, clearly demonstrating a seismic moment dependency. We confirmed positive correlations between equivalent parameters of the two approaches, that is, between and and between and . Moreover, we found that both approaches are appropriate for evaluating spectral decay characteristics, as long as the spectral decay parameters are appropriately evaluated by comparison with observed spectra. We examined the effects of the spectral decay characteristics on strong ground motion predictions, and demonstrated that simulated motions corrected using the model and those corrected using the model are almost the same. The results presented in this article contribute to improving predictions of high‐frequency strong ground motion.