Horio Yoshiharu (堀尾 吉晴, born 1543 and died July 26, 1611), was a daimyo of the Azuchi-Momoyama and Edo eras of Japanese history.
He was one of the three chūrō (arbiters) appointed by Toyotomi Hideyoshi. He is also the de facto first daimyo of the Matsue domain as he is the regent of his grandson. He is also known as Horio Mosuke (堀尾 茂助).
When Toyotomi Hideyoshi saw Yoshiharu, still young, wrestling with a giant boar, he took him into his service.
In 1567, Yoshiharu took part in the siege of the castle of Inabayama, under the orders of Hideyoshi. When Hideyoshi laid siege to Takamatsu castle in Bitchu province, Yoshiharu investigated how Shimizu Muneharu died.
In 1582, he took part in the battle of Yamazaki against Akechi Mitsuhide. On the eve of the battle, his own ninjas set fire to some buildings in the opposing camp. At the battle of Shizugatake, in 1583, he killed Saitō Toshimitsu after the latter tried to sneak behind Hideyoshi's lines.
In 1590, for his conduct at the siege of Odawara, Hideyoshi rewarded him by giving him the estate of Hamamatsu (Tōtōmi province) and 60,000 koku.
Horio Yoshiharu, Nakamura Kazuuji, and Ikoma Chikamasa were appointed chūrō by Hideyoshi in his last years, and participated in his administration. As chūrō, Yoshiharu participates in the work of the Izumo Shrine and the Houkou Temple (方広 寺, Hōkō-ji).
Yoshiharu pledged allegiance to Tokugawa Ieyasu after Hideyoshi's death in 15984. In 1599, he passed on the responsibility of head of the family to his son, Horio Tadauji, and received 50,000 koku in estates to live in after his retirement in Fuchu, Echizen province.
In 1600, Yoshiharu joined Ieyasu's forces. On August 27 at Chiryu in Mikawa province, he killed Kaganoi Shigemochi who had killed Mizuno Tadashige but was wounded by Shigemochi, which is why he could not take part in the battle of Sekigahara on October 21.
However, Ieyasu gave him 235,000 koku in Toda in Izumo province after the battle, because Yoshiharu killed Shigemochi and his son Tadauji passed off his exploits in the battle as his own.
In 1604, Yoshiharu's son Tadauji, who succeeded him as head of the family, died prematurely at the age of 26, and was succeeded by his grandson, Horio Tadaharu. Tadaharu was so young (9 years old) that Yoshiharu acted as godfather until his death.
The castle of Gassantoda was located in the mountains of Izumo province. From 1607 to 1611, Yoshiharu built a new castle, closer to the coast, in Matsue.
The quality of the building materials seems to attest to rather modest means. The estate ceded by Ieyasu now became the estate of Matsue, organized around its jōkamachi (castle town).
Yoshiharu is popular and so quiet that he is called Hotoke no Mosuke (仏の茂助), meaning that Yoshiharu is a saint.
The family temple of the Horio clan is the Shunkō-in, located in Hanazono, Ukyo District in Kyoto Prefecture.