Inba Tega Prefectural Natural Park, Prefectural nature park in Chiba Prefecture, Japan

Inba Tega Prefectural Natural Park covers 66.06 km² of northern Chiba Prefecture, centred on Inba Marsh, split into its north and west basins, and Tega Marsh, with its upper and lower parts. The designated area also takes in the Tega, Tone, Shōgen and Nagato rivers and the Inba Central Drainage Channel, while the Inba shortcut channel lies outside it. Open water, rice fields and the wooded slopes of the Shimōsa Plateau define the land.

The park was established as a prefectural protected area in 1952 to preserve the natural landscapes and water bodies in northern Chiba. This designation helped shield the lakes and their surroundings from major development.

The marshes are a wetland habitat for wild birds such as ducks and herons, and the park lists the Abiko City Museum of Birds and the Yamashina Institute for Ornithology among its facilities. Nearby municipalities run hands-on and citizens' farms around Tega Marsh, and the Tega Marsh biotope uses aquatic plants to clean the water as part of the Tega Marsh purification plan.

The park is spread across Kashiwa, Abiko, Inzai, Sakura, Narita, Sakae and Shisui. For Tega Marsh, the nearest stations are Abiko (JR Joban and Narita lines) and Kita-Kashiwa; for Inba Marsh, Inba-Nihon-Idai, Keisei-Sakura and Shimosa-Manzaki. Car parks exist at Tega Marsh Park and Inba Marsh Park. The Tega Marsh cycling road and riverside greenway link the main waterside facilities.

The park's 66.06 km² area includes the Tone River between Tega River and Shōgen River, but excludes the Inba shortcut channel. Within its bounds lie the Tega Marsh biotope, built to purify water with aquatic plants under the Tega Marsh purification plan, and the Yamashina Institute for Ornithology in Abiko.