The main gate of Kubota Castle called “Ichinomon,” was an important strategic location for the protection of the castle. The headquarters for the guards and a guardhouse were situated at the gate on the left side, providing the first of defense against attacks on the castle.
Construction on Kubota Castle began in 1603, and was completed in 1604. The main gate was first remodeled in 1622 and required additional repair several times later probably after incurring fire damage.
The present two-story wooden structure with tiled roof was rebuilt using historical records and archeological finds. Today, it stands as a tangible architectural reminder of the status of the Satake family during the Edo period.