Hachiōji Castle was built in the 1570s by Hōjō Ujiteru. It was constructed on a mountain, with many features located in strategic positions to deter an enemy force. Ujiteru left only 1,300 men behind at Hachiōji Castle when he went to help lift the Siege of Odawara (1590), which had been surrounded by Toyotomi Hideyoshi. Shortly thereafter, on June 23, 1590, more of Hideyoshi's forces, numbering 50,000 and led by Maeda Toshiie and Uesugi Kagekatsu, arrived to take the castle, which fell in just one day. Hideyoshi then commanded that the castle be destroyed, as he worried that it could be used against him. For years afterwards, the site remained abandoned because it was believed to be haunted.
The castle now lies in ruins, although in 1990 some stone walls, a bridge across a moat, and the entrance to the lord's palace were rebuilt. The national government has constructed a tunnel for the Ken-Ō Expressway through the mountain on which the castle is located.