PROBLEM TO BE SOLVED: To obtain both a composition for improving mental concentration used for improving the mental concentration during exercise and capable of suppressing psychological effects in psychogenic motor malfunction such as tension, atrophy, lowering or deficiency of concentration power or accumulation of mental fatigue and effectively and safely exhibiting essential sports performances during the exercise, and to provide a method for improving the mental concentration during the exercise. SOLUTION: This composition for improving the mental concentration is characterized by comprising theanine and is used for improving the mental concentration during the exercise. The method for improving the mental concentration during the exercise comprises administering the theanine to individuals.
