Komoro Castle (小諸城, Komoro-jō) is a hirayamashiro (hilltop castle) located in Komoro, Nagano Prefecture, Japan. The castle was constructed in 1554 by Takeda Shingen. In 1590, Sengoku Hidehisa became the lord. He was followed by his son, Sengoku Tadamasa. Tadamasa improved the castle, and the tenshu (keep)'s foundation dates from this time. The tenshu itself burned down during the Edo Period.