This paper investigated the L2 acquisition of Korean causative case marking and syntactic complexity by L1 English speakers. The nominative causee can be marked only in syntactic causative (‘-ke hata’ causative). Forty L1 English speakers of Korean and twenty one Korean native speakers have participated in the study. The acceptability judgment task was conducted in order to assess the learners' knowledge on the case marking of causee in the causative construction. For the task, two types of case marking-nominative and accusative- were distributed in syntactic and morphological causative constructions. A total of 44 items were created based on 11 verbs. The results showed that L2 learners had lower acceptability on the causative sentences with nominative causee compared to Korean native speakers. This implicates that not only the intermediate learners of Korean but also the advanced learners failed to acquire the native like case marking due to lack of recognizing syntactic complexity on Korean causative and the relying on their L1 knowledge on English causative.