State Road 104, is an IIA-class road in northern Serbia, connecting Novi Kneževac with Romania at Međa.

It is located in Vojvodina.

[1] Before the new road categorization regulation given in 2013, the route wore the following names: P 111, P 123, P 112, M 3, and O 6 (before 2012) / 100, 123 and 109 (after 2012).

[2][3] The existing route is a regional road with two traffic lanes.

By the valid Space Plan of Republic of Serbia the road is not planned for upgrading to main road, and is expected to be conditioned in its current state.