His chronic pulmonary tuberculosis is widely accepted to be the cause of death, and was stated in Jii onjuku kenmotsu shojo (literary remains of Warring States period) (Sengoku Ibun (ancient writings in Sengoku period), No.2638), pneumonia, stomach cancer or esophageal cancer (stated in "Koyo Gunkan").
死因に関しては、侍医御宿監物書状（戦国遺文2638号）にみられる持病の労咳（肺結核）、肺炎、『甲陽軍鑑』による胃癌若しくは食道癌による病死説が有力である。