The Hijikawa River originates in Masanobu, Uwacho, Higashiuwa-gun (Alt. 460m), runs down south on the Uwa Basin, then runs eastward, pass through the narrow mountain area, streams straight through the Ozu Basin, and finally flows into Iyonada.

The size of the drainage area is 1,210 square kilometers across one city, 11 towns, and two villages. It the largest first class river in Ehime prefecture, stretching over 103 km including tributaries such as the Kurosegawa, Funatogawa, Kawabegawa, Odagawa, and Yaochigawa rivers.

As to the natural conditions, the river is geographically unique, when compared with other rivers, as the 90% of the drainage area is on mountains. The only the plains are Uwa and Nomura in upper reaches and the Ozu Basin in the middle reaches, and with the exception of such, all the way down to the river mouth the mountains reach close to the river.

The distance between the source and the mouth is only 18 linear kilometers, for the stream makes a big-angle turn like an elbow (hiji in Japanese), which is said to have given the river this name.