A fluid for traction drives for automobiles which comprises (A) a hydrocarbon compound having two bridged rings selected from bicyclo[2.2.1]heptane ring, bicyclo[3.2.1]octane ring, bicyclo[3.3.0]octane ring and bicyclo[2.2.2]octane ring and (B) a hydrocarbon compound having at least one structure selected from quaternary carbon atom and ring structures and having a kinematic viscosity at 40.degree. C. of 10 mm.sup.2/s or smaller, and has a viscosity at -40.degree. C. of 40,000 Pas or smaller and a flash point of 140.degree. C. or higher, is provided. This fluid exhibits a great traction coefficient at high temperatures and very small viscosity at low temperatures. A fluid for traction drives which comprises a specific bicyclo[2,2,1]heptane derivative having 14 to 17 carbon atoms and having a viscosity index of 0 or greater is also provided. This fluid exhibits improved viscosity-temperature characteristics, decreased viscosity and improved fluidity at low temperatures.