| Ōyano-jima | |
| Map: | Japan |
| Native Name: | 大矢野島 |
| Native Name Link: | Japanese Language |
| Location: | Ariake Sea |
| Coordinates: | 32.5833°N 156°W [1] |
| Archipelago: | Amakusa |
| Area Km2: | 29.88 |
| Length Km: | 8 |
| Width Km: | 3 |
| Coastline Km: | 55.4 |
| Highest Mount: | Tobidake |
| Elevation M: | 229 |
| Country: | Japan |
| Country Admin Divisions Title: | Prefectures |
| Country Admin Divisions: | Kumamoto Prefecture |
| Country Admin Divisions Title 1: | City |
| Country Admin Divisions 1: | Kami-Amakusa |
| Population: | 14,729 |
| Population As Of: | 2005 |
| Density Km2: | 493 |
| Ethnic Groups: | Japanese |
, also spelt as Ōyanojima It is administered as part of the city of Kami-Amakusa. It is connected to the Japanese mainland since 1966 by Five Bridges of Amakusa.[2] The Japan National Route 266 passes through the island. The island primary industry is aquaculture of fish and shrimps. Large part of island belongs to Unzen-Amakusa National Park.
Ōyano-jima is an irregular shape, with a ragged, elongated outline oriented at north-south axis. The highest mount is which stands at 229 m. Ōyano-jima is the third largest island in the Amakusa group lying west of Kyushu, Japan. It is a northernmost island in the archipelago and serves as a gateway to entire Amakusa.
Ōyano-jima has a humid subtropical climate (Köppen climate classification Cfa) with very warm summers and mild winters. Precipitation is significant throughout the year; The summer tends to be Ōyano-jima's wettest season, with the tsuyu (梅雨 tsuyu, "plum rain") — the rainy season — occurring between early June (average:Jun.7) to late July (average:Jul.21).