The son of Seki Morinobu, lord of Kameyama Castle in Ise. Though he had become a monk on Mt. Hiei, he returned to lay life and inherited the family headship after his brother died in battle in 1582. Serving under Gamo Ujisato, he fought in the Kyushu and Odawara campaigns, earning a domain at Shirakawa. At Sekigahara he fought for the Eastern Army, and in 1609 was transferred to Kurosaka in Hoki, where he built Kagamiyama Castle. He also fought in the Siege of Osaka, but was stripped of his domain in 1618 due to discord among his retainers.

A daimyo with the unusual background of returning to lay life from the priesthood to inherit his family, he campaigned widely under Gamo Ujisato. In his later years he struggled to control his own retainers.

He built Kagamiyama Castle at Kurosaka in Hoki and laid out a castle town, though the castle was abandoned after only nine years. Short-lived as it was, it remains a historic site representing early-Edo castle building in eastern Hoki.