- Died: 1580
- Japanese: 別所 長治
Nagaharu was the son of Bessho Yasuharu. He was a damiyô of Harima province whose family had expanded following the decline of the Akamatsu clan, to which it was related. He initially aligned himself with Oda Nobunaga but following the rebellion of Araki Murashige severed his ties with Nobunaga. His domain was subsequently invaded by Oda forces under Toyotomi Hideyoshi. After resisting the Oda at Miki castle for two years (1578-1580), Nagaharu and his brother Tomoyuki committed suicide and thereby surrendered Miki to spare the lives of his men. Nagaharu had been married to a daughter of Hatano Hidemichi of Tamba province.