Andō Tadasue served as a bushō and sengoku daimyō during the Sengoku period. He was the fifth head of the Shimonokuni (Hiyama) branch of the Andō clan based at Hiyama Castle in Dewa Province.
The Andō clan originated from the environs of Tosaminato in Tsugaru in Mutsu Province, a gōzoku, or wealthy family, with operations in ocean transport to facilitate trade with the Emishi, or peoples of the Ezo territories. After losing in battle to the Nanbu clan, the Andō crossed to the Ezo territories within their sphere of influence. In 1456, Tadasue, together with Masasue, received an invitation from Andō Koresue, the commander of Akita Castle responsible for administration of the Ezo peoples in Dewa. Koresue was a member of a cadet family and landowner in the Akita District. In response to the offer from Koresue, Tadasue and Masasue moved to the Shōroku archipelago and, before long, decimated Kasai Hidekiyo in the Akita-Kahoku area. In 1488, Masasue encountered a rebellion by a retainer named Nagaki Yamato at Kahoku-Nukano Castle and took his own life, after which Tadasue inherited the clan.
In 1496, on the grounds of violent and unruly behavior, Andō Tsunesue (Shimonokuni Yamashiro-no-kami), a member of the family of the military governors of Matsumae on the southern tip of the Oshima Peninsula, was subject to claims from the local administrators including Kakizaki Mitsuhiro under his command. According to the wishes of these administrators, Tadasue gave instructions to Mitsuhiro (the son of his older sister) and, in the eleventh month, Tsunesue was attacked by a group under Tadasue (which may, in fact, have been Mitsuhiro’s own troops) and took his own life.
In addition to managing the affairs of the Emishi, Tadasue engaged in the development of his territory including renovations to Hiyama Castle on Hiyama-Kiriyama between 1494 and 1495 and the construction of the Nisshōzan-Kokusei Temple around 1504.
On 7/26 of Eishō 8 (1511), he died and was succeeded by his son, Hirosue. The reign of Tadasue was marked by discord with the Minato branch of the Andō owing to issues dating to the era of Tadasue’s father, Masasue, including territorial disputes over the Oga Peninsula and military conscriptions for several deployments to Tsugaru.