The purpose of this paper is to investigate whether the semantic feature (animacy) of the head nouns has influence on the acquisition of Korean head-internal relative clauses. To achieve these goals, a grammaticality judgement task has been conducted on 40 Korean speakers. Twenty test sentences were created according to four types of internally-headed relative clauses for a quantitative study. In this study, we found that Korean speakers judged the grammaticality of internally-headed relative clauses at a rate of around 50%, suggesting that they restrictively accept the existence of internally-headed relative clauses. We also found that object internally-headed relative clauses with an inanimate head were judged more correctly than those with an animate head which indicates that the animacy effect only work on the acquisition of object internally-headed relative clauses. The fact that the animacy of head nouns has a limited influence on the acquisition Korean internally-headed relative clauses suggests that there is some interrelation between head nouns’ animacy and the acquisition of internally-headed relative clauses in Korean.