Mizoguchi Naoaki (溝口直諒, February 12, 1799 – July 28, 1858) was the 10th daimyō of Shibata Domain in Echigo Province, Japan (modern-day Niigata Prefecture).

Due to his youth, the rōjū Matsudaira Nobuakira of Yoshida Domain served as regent until 1813.

Once Naoaki took control of the domain, he revived his predecessors fiscal austerity programmes; however, due to a fire which burned down much of the Shibata jōkamachi, the Sanjō earthquake and the Tenpō famine, he was not able to make much progress in reforming the financial situation of the domain.

In his retirement, he establish a school in Tokyo and wrote several works on various topics including education, maritime defense and the theory of labor.

Naoaki was married to a daughter of Asano Narikata of Hiroshima Domain, and after her death, remarried to her younger sister.