Provided is a preventive agent which is for a growing child's anxiety, attributable to stress in infancy, and which is to be taken by an infant who has stress in infancy. Provided is a preventive agent for a growing child's anxiety, attributable to stress in infancy, or a food composition for preventing a growing child's anxiety, attributable to stress in infancy, and the preventive agent or the food composition contains lactoferrin and/or a lactoferrin degradation product as an active ingredient and is characterized by being used in such a manner that lactoferrin and/or a lactoferrin degradation product is to be taken during infancy by an infant who was normal at birth and has stress in infancy.本發明提供一種藉由使於乳兒期遭受壓力之乳兒攝取而對起因於乳兒期壓力之成長期焦慮行為的預防劑。 一種起因於乳兒期壓力之成長期焦慮行為的預防劑或用以預防起因於乳兒期壓力之成長期焦慮行為之食品組成物，其特徵係對於出生時健康兒且於乳兒期遭受壓力之乳兒以於乳兒期攝取乳鐵蛋白及/或乳鐵蛋白分解物之方式使用，且含有乳鐵蛋白及/或乳鐵蛋白分解物作為有效成分。
