Abstract: An automatic transmission fluid composition is provided which has significantly higher coefficients of dynamic friction (.mu.d) and static friction (.mu.s) than those of the conventional automatic transmission fluid. In addition, the composition has a .mu.o/.mu.d ratio close to 1.0, and a small change with the passage of time in frictional properties. The automatic transmission fluid composition comprises 0.01 to 20% by weight of an overbasic oil-soluble metal salt (a) prepared by use of an alkaline-earth metal borate, and 0.01 to 15% by weight of a compound (b) having a long-chain alkyl group and an amino group in the same molecular structure on the basis of the total amount of composition as essential components, the balance being lubricating base oil.