Dirskovski joined the DMA in September 1997 after a long career working in publicity, marketing and sales in the magazine, newspaper and telemarketing sectors.
He was appointed DMA's head of interactive media in 2004 and since then has been responsible for driving policy in the areas of email and mobile marketing, telemarketing, interactive TV and search marketing.
Dirskovski is currently contemplating how he will spend his retirement.
For the interim his position will be covered by Robert Keitch, director of media channel development.
James Kelly, managing director of the DMA, said that Dirskovski made an "invaluable contribution" to promoting the interests of the interactive media sectors.
He said: "It's been a pleasure working with Robert over the years. His keen insight and understanding has ensured that the DMA has been at the forefront of policy development for the interactive media sector.
"This has been particularly important at a time when these new and emerging marketing channels are at an early stage of development. I and all at the DMA wish him the very best for the future."