Komatsu castle was a lowlands flatlands castle (hirajiro) in Kaga province.
It was built in 1576 by Wakabayashi Nagato, the site having already come to be known as Komatsu after the Kaga Ikki leader Komatsu Michihide. Built largely on swamp, roughly 30% of the land area of the castle grounds was comprised of moats or ditches.
Niwa Nagashige came to control Komatsu in 1597; it was valued at 120,000 koku at the time. However, as he sided with Ishida Mitsunari at the battle of Sekigahara, he soon lost his territory to the Maeda clan.
Komatsu became the retirement home of Maeda Toshitsune, third daimyô of Kaga han, in 1639. Despite the shogunate's "one castle per domain" policy, Komatsu was allowed to be maintained alongside the domain's chief castle at Kanazawa until 1872, when the han system was abolished and Komatsu, along with a great many castles across the country were demolished.
- Terada Shôichi (ed.) Meijô wo aruku 2: Kanazawa-jô. Tokyo: PHP Kenkyûsho, 2002.