The Aso Onda Festival is an annual traditional festival passed down through the generations which honors the pioneering god of Aso for opening the region to agriculture and prays for good harvests.

It has been a regular festival of Aso Shrine since the Meiji Era, and a large Shinto ritual is held on the occasion: July 26 at Kokuzou Shrine and on July 28 at Aso Shrine.