Nanbu Toshimoto (南部利幹, 11 March 1689 – 13 July 1725) was a mid-Edo period Japanese samurai, and the 6th daimyō of Morioka Domain in northern Japan.

[1] Toshimoto was the 4th son of Nanbu Yukinobu, the 4th daimyō of Morioka Domain.

[1] He was received in formal audience by shōgun Tokugawa Tsunayoshi on 15 January.

At this time the domain was suffering from severe financial difficulties due to reduced production from its copper mines and was deeply in debt, so much so that expenses for the mandatory sankin-kōtai procession could not be met.

In 1723, he took the drastic and highly unpopular step of reducing the number of retainers.