According to a spokeswoman, Steve Wilhite's resignation is effective immediately. His replacement has not yet been named, she added.
In his position, Wilhite oversaw advertising, marketing communications and online marketing. He was Apple's primary contact with TBWA/Chiat/Day, the company's advertising agency.
Image and marketing has always played a crucial role at Apple. The company's famous "1984" ads helped launch the first Macintosh computer, while the company's "Think Different" campaign helped make the colorful iMac computer line a success. One analyst once described the company as an advertising agency that also sells computers.
Apple's Web site describes Wilhite as "the man singularly responsible for protecting and promoting the Apple brand."
The resignation follows the October departure of Mitch Mandich, senior vice president of worldwide sales. Mandich's resignation came after a revenue warning from the PC company.
In late September, the company warned revenue would be substantially below expectations because of low sales in Europe and less-than-strong demand for its G4 Cube computer.
The numbers for the fourth fiscal quarter, when reported, were worse than expected, as the company earned 30 cents per share on sales of $1.87 billion. Analysts had expected the company to report earnings of 31 cents per share. At that time, Apple also instituted a hiring freeze.
Apple shares closed down 31 cents, or 1.6 percent, to $18.50 on Wednesday. Shares have traded as high as $75.18 and as low as $17.50 in the past 52 weeks.