Nagahama Castle (長浜城, Nagahama-jō) is a hirashiro (castle on a plain) located in Nagahama, Shiga Prefecture, Japan.

Nagahama Castle was built in 1575-1576 by Hashiba Hideyoshi (later known as Toyotomi Hideyoshi) in the village then called Imahama, renaming the area Nagahama.

Hideyoshi was succeeded as lord by Yamanouchi Kazutoyo after the 1583 Battle of Shizugatake.

Kazutoyo was then replaced by Naito Nobunari after the Battle of Sekigahara in 1600.

Most of the castle lies in ruins, but the tenshu (keep) was reconstructed out of concrete in 1983.