Although hypnotic drugs are often suggested for short-term use, prolonged usage of the hypnotics are common in clinical settings. There has been a concern that whether this practice will lead to drug dependence. Attentional bias to drug-related cues has been indicated as an important factor in substance dependence. This study aims to examine the attentional bias toward hypnotics in long-term hypnotic users by measuring event-related potential (ERP) elicited by hypnotic-related pictures.