In its monthly report, released on Wednesday, the service said the number of people freshly out of a job increased compared to August, but so did the number of those who found a job.
A total of 5,732 were newly registered as unemployed, 20.4% more than in August, but 7.4% fewer than in September 2017.
More than half (2,942) saw their fixed-term contracts expire and another 1,127 were first-time job seekers.
Out of the 7,871 who were checked out of the unemployment roll in September, 5,850 found a job or got self-employed. This is as much as 80.9% more than in August, but 8.9% fewer in September 2017.
All regional offices registered a decline in joblessness. Year-on-year the most substantial drops were recorded at the units of Nova Gorica (-12.3%) and Murska Sobota (-11.8%).
In the first nine months of the year an average 78,980 were registered as unemployed, 12.6% fewer than in the same period a year ago.