This region has a very long histroy, many ruins and relics from Jomon Period were discovered. In addition, the high cultural level was known by the discovery of the national treasure "Mirror of Portrait" that is owned by the Sudahachiman Shrine which is famous for its oldest epigraphy (Kinseki Bun) and the important cultural property "Nara Ceramic Pot" which thought to be the urn for magnate's child.

In between Asuka period and Nara period, there used to be gates on Mt. Matsuchi to connect people from Yamato (the old capital) to Kii, many poets used to visit that place, and thus many poems were remained in that area. In addition, during medieval times, Mt. Koya was prosperous due to its Hotel Town on Koya Street on the way from Kyo to Mt. Koya, nowadays the traditional style of the city is still remained in Kiimitoge and Shimizu, etc.

The city named Hashimoto is a territory taken from Hideyoshi by the priest of Mt. Koya named Mokujiki Ogo about 400 years from now in Tensho Era 15 (1587), since then the development of this town began.
Priest Ogo built a 235m long bridge in Kinokawa, people then called Hashimoto "Near the Bridge", thus it was then called "Hashimoto". In a few years, the city received "Permission for salt selling" and "Permanent Exemption", since then the city was developing rapidly.
After the death of Hideyoshi, the city experienced temporary decline, however once entered the Edo era, it became the center as the shipping port, a place where the traditional messenger come and go between Yamato Street and Koya Street and the market for local produces.

In Meiji 5, when the government decided to abolish domain "Han" and employ prefecture "Ken" system, Hashimoto became part of Wakayama Prefecture. In Meiji 22, Hashimoto became a town and in Showa 30, Hashimoto was merged with nearby 6 cities and Villages, became Hashimoto City. On 1 Mar, Heisei 18, once again it merged with Koyaguchi Town, and became the present "Hashimoto City", and welcomed a new start.