A suit was also filed in Illinois to gain ballot access there, the Nader campaign said.
The Nader campaign said the Michigan suit was filed late Tuesday in federal court in Detroit.
"Ralph Nader is the nominee of the Reform Party and he is entitled to appear on the Reform Party's ballot line in Michigan," Nader's attorney, Bruce Afran, said in a written statement. "Anything less is a violation of Nader's constitutional rights."
Democrats fear Nader's candidacy could draw support away from John Kerry in a close race with President Bush.
Michigan Secretary of State Terri Lynn Land has so far rejected giving Nader a ballot spot because there is a dispute over who represents the Reform Party in Michigan.
Nader also has a chance to qualify for the Michigan ballot as an independent. State officials are reviewing a challenge to that candidacy from the Michigan Democratic Party.
More than 50,000 signatures were submitted to state election officials on Nader's behalf, with most coming from the Michigan Republican Party.