The TI Circuit Aida (Present: Okayama International Circuit) is a 2.301-mile (3.7 km) private motorsport race track near Aida (Present: Mimasaka), Okayama Prefecture, Japan. TI is abbreviation of "Tanaka International" after the name of the holding company, though the name of the circuit was officially "TI Circuit Aida".

The course was built in 1992 as a private race track for the wealthy. It soon hosted its first race, staged by veteran British drivers (which explains the circuit's corner names, such as Hobbs and Attwood).

In 1994 and 1995, the TI Circuit hosted the Formula One Pacific Grand Prix; both events were won by Michael Schumacher in his early title-winning years. This race made Japan one of only five countries to ever host more than one Formula One event in the same year. It was discontinued primarily due to its location in a remote area of Japan.

In March, 2003, Tanaka International Company sold the circuit to Unimat, and the new owners renamed it Okayama International Circuit on May 1, 2004.

On October 26 2008 the circuit will host a round of the FIA World Touring Car Championship. It will be the first world championship FIA race since 1995