PROBLEM TO BE SOLVED: To provide prophylactic agents for anxiety behavior during growth phase caused by stress during infant phase, the agent being ingested by an infant who receives stress during infant phase.SOLUTION: Provided is a prophylactic agent for anxiety behavior during growth phase caused by stress during infant phase, the agent being characterized by being used so that lactoferrin and/or a lactoferrin degradation product is ingested by an infant who is healthy at birth and receives stress during infant phase, and the agent containing lactoferrin and/or a lactoferrin degradation product as an active ingredient; and a food composition for preventing anxiety behavior during growth phase caused by stress during infant phase.SELECTED DRAWING: NoneCOPYRIGHT: (C)2018,JPO&INPIT【課題】 乳児期においてストレスを受ける乳児が摂取することによって、乳児期のストレスに起因する成長期の不安行動の予防剤を提供すること。【解決手段】 ラクトフェリン及び/又はラクトフェリン分解物が、出生時健常児でありかつ乳児期においてストレスを受ける乳児に対して、乳児期に摂取されるように用いることを特徴とする、ラクトフェリン及び/又はラクトフェリン分解物を有効成分として含有する、乳児期のストレスに起因する成長期の不安行動の予防剤又は乳児期のストレスに起因する成長期の不安行動を予防するための食品組成物。【選択図】なし