[1] On the death of his father in 1620, he became daimyō of Shinano-Nakamura Domain (10,000 koku), taking the name of Iwaki Yoshitaka.

This was a small domain in what is now Nagano Prefecture, awarded to the once illustrious Iwaki clan after the Battle of Osaka.

In 1622, his kokudaka were increased by 10,000 koku in Yuri District, Dewa Province, and in November 1623, he moved his seat from Shinano-Nakamura to that location, where he built a jin'ya.

Yoshitaka was awarded an estate of 50,000 koku in November 1630 by his adoptive father, who exhibited no signs of intending to retire or relax his control over Kubota Domain.

On December 28, 1666, his court title was promoted to “General of the Left Imperial Guard” (左近衛少将).