There are daily flights (except Saturdays) from Oslo Airport Gardermoen with Widerøe to Røros Airport. You may also charter a plane to Røros Airport, something that Røros Flyservice will be happy to arrange for you.
Alternatively, fly to Trondheim Airport Værnes and drive a rental car to Røros, or take the bus or train.
There are regular departures both from Oslo and Trondheim with the Norwegian State Railways (NSB).
Gauldal Billag offers regular routes and is able to provide chartered buses on request. The company provides an express bus between Trondheim and Røros. Gauldal Billag can be contacted on phone + 47 72 40 62 00.
Nor-Way Bussekspress offers regular routes between Oslo and Røros and Trondheim and Røros.