TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Material: In the material, a primary particle of lithium titanate (I) is aggregated together with a magnesium compound to form aggregations (secondary particles); several primary particles of lithium titanate (I), in which the surfaces of primary particles are covered with a magnesium compound, is aggregated to form aggregations (secondary particles); and a weight ratio of magnesium atoms to lithium titanate (I) is 0.1-5 wt.% Preferred Process: The wet mixing process is carried out by mixing a lithium titanate material with a magnesium compound material in an aqueous solvent, while wet-grinding a solid in the slurry using a granular medium. The heating process is carried out by spraying the aqueous slurry in a spray dryer. The lithium titanate material is obtained by mixing materials for preparing lithium titanate to prepare a mixture of a lithium compound and titanium dioxide which is obtained by a sulfuric acid method and has a specific surface area (based on Brunauer, Emmett and Teller (BET) method) of 1-50 m2/g, and baking the mixture of lithium compound and titanium dioxide obtained by the mixing materials for preparing lithium titanate at 600-900 degrees C to obtain lithium titanate. Preferred Components: The magnesium compound is magnesium oxide, magnesium phosphate or magnesium sulfate. The magnesium compound material is a water-soluble magnesium compound. The mean particle diameter of primary particles of the lithium titanate (I) is less than or equal to 2 mu m. EXAMPLE - Titanium dioxide (mean particle diameter of 5.2 mu m, BET specific surface area of 29.8 m2/g, rutilization ratio of less than or equal to 5%) obtained by a sulfuric acid method and lithium carbonate (Li2CO3, mean particle diameter of 8.2 mu m) were mixed such that a molar ratio (Li/Ti) of lithium atoms in lithium carbonate to titanium atoms was 0.800, followed by wet-mixing. Then, the resulting mixture was baked in the air at 850 degrees C for 5 hours, cooled and disintegrated to obtain lithium titanate of formula Li4Ti5O12 having Li/Ti molar ratio of 0.800. Then, the obtained lithium titanate was dispersed in pure water such that a solid concentration was 40%. Then, magnesium oxide (mean particle diameter of 0.5 mu m) (1.20 wt.%) was added, and the mixture was wet mixed, until the mean particle diameter of solid in a slurry reached 0.5 mu m, to obtain an aqueous slurry. The aqueous slurry was sprayed using a spray dryer whose inlet temperature was set at 200 degrees C to obtain an anode active material for lithium secondary batteries. The obtained anode active material showed Brunauer, Emmett and Teller (BET) surface area of 4.7 m2/g.