Steve Finlan, acting head of Gap Europe, will leave at the end of April to become Thomas Cook managing director of sales.
Finlan has held the Gap role since the departure of former head of Europe Anthony Thompson, who became head of childrenswear at Marks & Spencer in August.
News of his exit followed the arrival of Andrew Rolfe as president of Gap International two weeks ago. Rolfe was appointed in November last year.
A spokeswoman said: 'We are looking to replace Finlan, but Rolfe has only been in the position for two weeks and he is still in the process of reviewing and assessing all opportunities.'
Gap announced two weeks ago that it was withdrawing from the difficult German market, and will complete its exit by August 1.
However, the spokeswoman said part of Rolfe's remit was to assess opportunities for international growth in Europe and beyond. She said Gap chief executive Paul Pressler views the international division as 'the growth engine for the business'.
Outside North America, Gap has shops in the UK, France and Japan, but has not yet launched its sub-brands, Blue Navy and Banana Republic, overseas.
Recent figures suggest Gap has halted the sales decline that had blighted the retailer in recent years. Prior to the difficulties there had been speculation that Gap would launch of one of its sub-brands in the UK.