Stephen Toulouse, the director of policy and enforcement for Xbox Live, will leave his role on February 15.
"This is a positive thing," he said on his personal blog.
"I have nothing but confidence in the future of Microsoft and specifically Xbox and Xbox Live. I have enormous gratitude for my time there. I want to finish my next book, and explore other opportunities."
He also stated that the departure will not cause any interruption to the Xbox service.
Toulouse has been with Microsoft for 18 years, working on the launch of Windows 95, training support engineers and managing security issues for Xbox.
"My reasons for leaving are complex and personal, but the parting could not be more amicable. I continue to believe this place makes great technology, and I am absolutely thrilled for the future of Xbox and Xbox Live."