The first lord of Tsugaru Domain, Tamenobu Tsugaru[津軽為信（つがるためのぶ）](1550-1608) originally belonged to Nanbu[南部（なんぶ）] clan who had ruled present Aomori and Iwate Prefecture. In 1588, Tamenobu occupied Tsugaru Region.and he was independent of Nanbu clan.
In 1603, Tamenobu began constructing the castle in the present place but he died one year later. The construction stopped but Nobuhira Tsugaru[津軽信枚（つがるのぶひら）] who was a Tamenobu's son and the second lord of Tsugaru Domain restarted that and the castle completed in 1611.
The Tenshu[天守（てんしゅ）](main keep tower, a.k.a. Tenshukaku[天守閣（てんしゅかく）], Tenshu was an important facility not only for the defense but also as a symbol of the castle.) was the five-storied building but that was burnt down due to a lightning strike in 1627.
At that time, Hirosaki was called "Takaoka[鷹岡 or 高丘（たかおか）]". Therefore, the castle was called "Takaoka Castle"(This name is also used as another name of Hirosaki Castle now).
In 1628, Takaoka was renamed Hirosaki by a high bonze, Tenkai[天海（てんかい）] and the Castle also came to be called "Hirosaki Castle".
Tenshu was not reconstructed for a long time. Because the construction of new Tenshu was severely restricted by Buke-shohatto[武家諸法度（ぶけしょはっと）](Laws for the Military Houses) in the Edo Period(1603-1868).
But the ninth lord, Yasuchika[寧親（やすちか）] rebuilt Tenshu as a three-storied building in 1810. The Tenshu was reconstructed by reforming a Yagura[櫓（やぐら）](watch tower) which had been at the place. It is said that the reconstruction was permitted due to the contribution to the security of Ezo-chi[蝦夷地（えぞち）](present Hokkaidō) and for the purpose of defending the Tsugaru Strait(The strait between Aomori and Hokkaidō) against Russian ships.
This Tenshu is in existence. Remaining Tenshus in Japan which were built until the Edo Period were only twelve and the Tenshu of Hirosaki Castle is the only one in Tōhoku Region. Other than this Tenshu, three Yaguras and five gates remain and they have been registered as Important Cultural Properties. And the castle site is maintained as Hirosaki Park.
In 2015, Tenshu was towed to the 70 meters point from the original place due to the restoration work of stone walls. That is still being under construction and it is said to take about 10 years.
Hirosaki Park is a famous spot of Sakura blossoms and about 2600 Sakura trees such as Somei-Yoshino[ソメイヨシノ] and Shidare-zakura[シダレザクラ] are planted.
You can see the beautiful scenery of the castle with Sakura blossoms in late April and they are illuminated at night.
Especially, this park is known as a famous Hana-ikada[花筏（はないかだ）](floating Sakura petals on the water) spot. In the late season of Sakura blossoms, the moat is covered with pale pink Sakura petals.
And there is an oldest Somei-Yoshino tree which is about 120 years old in the park.