The present invention relates to a lactoferrin-conjugated nanoparticle complex and a novel use thereof. In the nanoparticle complex according to the present invention, lactoferrin or polyethylene glycol-lactoferrin is bound to metal nanoparticles, and according to this construction, it can be confirmed that the metal nanoparticles are not only efficiently targeted to the brain tumor tissues, but also the stability of the metal nanoparticles can be maintained even in the in vivo conditions, and thus it is expected in the treatment of brain tumors to be treatable to targets by approaching more fundamentally.