This is a set of data of an manuscript of “Lung density on post-mortem computed tomography using three-dimensional data: A comparison between fresh-water and salt-water drowning.” Postmortem computed tomography (PMCT) is increasingly used rather than autopsy in some countries. Previously, the difference between the findings of PMCT among cases of fresh-water and salt-water drowning had been reported, but the density (CT number) of the lungs was not compared. Therefore, we investigated the density of whole lungs between fresh- and salt-water drowning cases in this article, to address this shortcoming. Using three-dimensional data, we found a higher PMCT density (CT number) in the whole lungs of individuals who drowned in sea water than in those who drowned in fresh water. This may reflect differences in phenomena occurring during drowning, including the severity of pulmonary edema, particularly interstitial edema, between the two types of drowning.