Mike Soutar is planning to set up a publishing venture and has left his role as IPC Media's editorial director.
Soutar, who launched the men's weekly Nuts and the celebrity title Pick Me Up and redeveloped Woman, will be on gardening leave for six months.
Details of his new venture have yet to emerge.
Soutar said: "IPC has asked me to take gardening leave as part of my contractual obligations to sit out notice."
IPC was tight-lipped on Soutar's abrupt departure, issuing no advanced warning of the move, and said in a statement: "After six years with the company, group editorial director Mike Soutar has decided it's time to leave IPC.
"In accordance with the terms of his contract, Mike is stepping down from the board and taking gardening leave with immediate effect."
The departure of such a high-profile executive at such seemingly short notice is unusual, and his exit has come as a surprise to many.
Sylvia Auton, IPC's chief executive, had not made a statement on Soutar's replacement as Campaign went to press, but it is understood that, in the interim, his duties will be covered by the creative director Andy Cowles.
Soutar began his career at Emap and became the youngest-ever editor of Smash Hits in 1991. When Emap bought FHM in 1994, he became the editor, and saw its circulation increase from 50,000 to 500,000 in less than three years.
After FHM, he moved to the radio station Kiss 100 as its managing director.
He left his role as the editor-in-chief of Maxim in the US to join IPC in 2000 as the managing director of IPC Music and Sport.
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