To obtain an automatic transmission fluid compsn. which has a high static friction coefficient and an excellent durability while retaining a low dynamic friction coefficient ratio by compounding a lube base oil with a sulfurized alkaline earth metal salt mixture of a hydroxyalkylbenzoic acid and an alkylphenol.

This compsn. is obtd. by compounding a tube base oil comprising a mineral oil, a synthetic oil, or their mixture and having a kinematic viscosity of 2-10mm2/sec at 100°C with 0.1-3wt.% sulfurized alkaline earth metal salt mixture of a hydroxyalkylbenzoic acid and an alkylphenol and, if necessary, further with additives for imparting fundamental characteristics of an automatic transmission fluid to the compsn. The obtd. compsn. has a kinematic viscosity of 5-10mm2/sec at 100°C and 20-50mm2/sec at 40°C, has a high torque transmission capacity while retaining capability of preventing gear change shock, and is excellent in durability.