The final Markit/Nikkei services Purchasing Managers' Index (PMI) for Japan fell to 51.6 in November from 52.2 in October.
A reading below 50 indicates contraction of activity.
The decline was driven by a weaker growth in activity and new business.
"Business activity at Japanese services firms increased at a slower rate in November, underpinned by a softer expansion in new orders. Subsequently, employment levels fell for the second month running," economist at Markit, Amy Brownbill, said.