Mr De Pury, who will pursue new interests, had been at the helm of the company for 12 years, focusing auction activities in New York and London on Contemporary art, design, jewellery and photography.
His departure brings to an end an eventful history with the firm that saw him first take over Phillips in 2000 under its then owner, the French billionaire entrepreneur Bernard Arnault. Mr De Pury stayed to run the rump of the company when much of Phillips was sold to Bonhams in 2001, buying out Arnault's remaining stake in 2003 with his then partner Daniella Luxembourg and changing the name to Phillips de Pury Luxembourg.
Soon after, they opened a new London saleroom in Victoria with plans for sales of Contemporary art, photography and jewellery.
In 2004, Ms Luxembourg sold her stake and left to launch an art investment company, with the firm changing its name once more, this time to Phillips de Pury & Company. The Moscow-based luxury retail giant Mercury Group bought a majority stake in the autumn of 2008, with Mr De Pury remaining as chairman.
With his departure, the firm will now revert to the original name of Phillips, and Mercury have announced expansion plans for February at their Park Avenue headquarters in New York "by taking significant additional gallery and office space", perhaps a signal that they aim to compete more vigorously in the field of private treaty sales, the area of activity that has become the central battleground between Christie's and Sotheby's in recent years.