Oakland A's star pitcher Vida Blue yesterday filed suit against his boss, Charles O. Finley, seeking $1.5 million in damages and the invalidation of his three-year contract with the embattled club.

The suit, filed in Alameda County (Calif.) Superior Court, accuses Finley of fraud, bad faith an undue influence during contract negotiations last year during Finley's unsuccessful attempt to sell Blue's contract to the New York Yankees.

Blue, who would have become a free agent at the season's end if he had remained unsigned, charges Finley told him he would not be worth more than $485,000 on the free-agent market while Finley knew Blue's services for three years would be worth $1,985,000 in the American League.

Upon learning of the suit, Finley said, "I don't care to dignity any of his statements with comment. If he sued, he sued. What else is new? You can quote me on that. What else is new?"

Finley and Blue, one of the last players remaining from the three-time World Series champion A's have been sparring verbally for months. Blue's discontent with Finley prompted him to walk out of spring training for three days this year.

In his suit, filed by attorney Richard F. Sequeria, Blue also charges Finley had promised him he would remain with the A's for the duration of the contract while the A's owner was trying to sell his contract.

The Yankees agreed to pay Finley $1.5 million for Blue's contract last June 15 if Finley could sign him. Minutes before the trading deadline that night, Finley signed Blue and sold the contract to the Yankees.

Baseball commissioner Bowie Kuhn nullified the sale, which was part of a three-player $3.5 million package. Claiming he needed the cash to rebuild his club, Finley sued Kuhn and lost.