After passing away in 1645 aged 83, he was buried at Koto-in Temple according to his will and it later became patronized as the ancestral temple of the Hosokawa clan.
正保2年（1645年）に83歳で没した三斎は遺言により高桐院に埋葬され、以後細川氏の菩提寺として庇護される。