The American Airlines plane was flying from the South Korean city of Incheon to Dallas when the turbulence hit.
Five people needed hospital treatment, the airline said, but none of the injuries were life-threatening.
The turbulence, which occurred about 75 minutes into the flight, caused food to be thrown around the cabin.
“Medical personnel have been able to evaluate all passengers and crew members asking for medical attention,” the airline said.
“Four passengers and one crew member have been transported to local hospitals for further observation and treatment.”
A male flight attendant was thrown to the ceiling, hitting his head, Kyodo news agency said, citing a passenger.
“We were eating and all the food just flew up in the air and pretty much bounced off and fell. There were carts all over the place,” another passenger told local media.
The plane landed at Tokyo’s Narita airport in the early hours of Wednesday. It was expected to continue on to the US later in the day.