Provided is a lubricating oil composition for manual transmissions which has anti-seizure properties for shift forks and can provide manual transmissions with excellent shifting characteristics though it has a low viscosity and can save fuel to be used in automobiles. The lubricating oil composition for manual transmissions comprises a lubricating base oil with a kinematic viscosity at 100° C. of 4 to 6 mm2/s, on the basis of the total mass of the composition, (A) 0.14 to 0.20 percent by mass in terms of magnesium of magnesium sulfonate, (B) 0.14 to 0.18 percent by mass in terms of zinc of a specific zinc dithiophosphate, (C) 0.3 to 0.5 percent by mass in terms of sulfur of a sulfur-containing extreme pressure additive other than zinc dithiophosphate, and (D) 0.02 to 0.05 percent by mass in terms of phosphorus of an alkyl phosphite, and having a kinematic viscosity at 40° C. of 25 to 30 mm2/s.