Bessho Nagaharu(別所長治; 1558-February 2, 1580) is a eldest son of Bessho Yasuharu.

On 1578 when Oda Nobunaga called on his retainers to attack Mori clan, Nagaharu had almost decided to lead Oda troop but after hearing that Hashiba Hideyoshi who he did not count highly because of his lowly birth, revolted allying himself with Hatano Hideharu of Tamba province.

This led to Nagaharu besieged by Hideyoshi's troop by the order of Nobunaga. Nagaharu took stand in Miki Castle starting the Siege of Miki. The siege did not go well for Hideyoshi and with a revolt by Araki Murashige and help of Mori clan, he succesfully repeled the Oda troop. But Hideyoshi returned and this time instead of launching a direct assault, he launched multiple sieges against smaller castles like Kamiyoshi Castle and Sigata Castle to cut off the support from Mori. This led to a rapid depletion of food, and on 1580 with no hope of another reinforcement from Mori clan, Nagaharu committed seppuku in exchange for lives of troop in Miki Castle.