1. Provided are: an extract fraction with an increased content of ginsenoside RG3 by extracting ginseng with water or ethanol, eluting the obtained extract on an adsorption resin to obtain a substrate ginsenoside extract fraction, and treating the obtained extract fraction with heat, pressure and a pH of predetermined conditions; a dietary supplement composition for improving memory or concentration; and a pharmaceutical composition for preventing and treating lapse of memory or concentration, containing the extract fraction as an active ingredient.