Kazuki Nakajima, whose Toyota links helped secure a Williams race seat from the last race of 2007 until the end of 2009, will now join the Japanese manufacturer in leaving F1.
Already out of a drive at Williams, the failure of Stefan GP to land a place on the 2010 F1 grid has brought at least a temporary end to Nakajima's F1 career.
"With Stefan GP not gaining approval my plans are unclear," Nakajima told his official website. "I will keep looking forward and spend some time below the surface keeping busy and concentrating on how to secure a quick return."
After claiming nine points in 2008, Nakajima failed to score last season, when team-mate Nico Rosberg racked up 34.5 points. Rosberg has joined Mercedes for 2010, when Williams will field the all-new line-up of Rubens Barrichello and Nico Hulkenberg.
Nakajima's exit leaves BMW Sauber's Kamui Kobayashi as the only Japanese driver on the 2010 F1 grid.