The Ayamezuka Kofun is located on the tip of a plateau on the east foot of Mount Kakuda, a 482-meter hill in far western Niigata city, within the grounds of a Buddhist temple called Kanzen-ji. It is a , which is shaped like a keyhole, having one square end and one circular end, when viewed from above. The tumulus has a total length of 53 meters, making it one of the largest in Niigata Prefecture, and marking the northern limit at which keyhole-shaped kofun have been found on the Sea of Japan coast. The posterior circular portion has a diameter of 33 meters and height of three meters, and the anterior rectangular portion has a width of 18 meters and height of two meters. The tumulus was surrounded by circumferential moat, with dirt from the moat used to partly construct the tumulus.
