A transmission oil composition for an automobile characterized in that it contains a base oil selected from the group consisting of a mineral oil, a synthetic oil and mixtures thereof; and a phosphate compound selected from the group consisting of (A) a zinc dithiophosphate having a hydrocarbon group, (B) a triaryl phosphate (C) a triaryl thiophosphate, and mixtures thereof at 0.1 to 15.0% by mass with respect to the total composition; wherein the composition has a volume resistivity of 1.times.10.sup.7 ohmm or more at 80.degree. C.