To obtain a traction drive fluid for automobiles having high coefficient of traction, excellent in low temperature fluidity, having high viscosity index and excellent also in boundary lubricating property and oxidation stability.

A traction drive fluid feathuring compounding a base oil composed of the following components A and B and containing 1-30 wt.% component A with the following components C and D. (A): a polyorganosiloxane containing phenyl group, having 20-500 mm2/s kinematic viscosity at 25°C. (B): a hydride of α-alkylstyrene dimer. (C): 0.2-3.0 wt.% at least one kind of compound selected from thiophosphate and thiophosphite. (D): 0.2-2.5 wt.% zinc dithiophosphate.