Background and Objectives: Preoperative anxiety is a common emotional response before elective surgery that influences postoperative outcomes and can increase analgesic requirements. However, clinicians frequently overlook these concerns. This study aimed to quantify preoperative anxiety and evaluate its association with patient-related factors. Materials and Methods: Anxiety levels were evaluated in adult patients awaiting elective surgery using the Korean-translated version of the Amsterdam Preoperative Anxiety and Information Scale (APAIS) and the State-Trait Anxiety Inventory-Korean YZ form (STAI-KYZ). The patients were also surveyed regarding the subjective causes of preoperative anxiety. Results: The study found that a total of 55 adult patients had a well-balanced subject distribution. Both questionnaires showed high internal consistency (Cronbach’s alpha values of 0.85 and 0.93). Significant correlations were observed in situational anxiety scores from the questionnaires, indicating differences between groups with high trait anxiety and those with normal anxiety levels (p < 0.05). Notably, female sex was the only patient-related factor that significantly affected the anxiety scores (p < 0.05). Furthermore, when considering additional patient factors stratified by sex, it became evident that younger females and females with prior general anesthesia experience displayed higher anxiety levels than their male counterparts. The most commonly reported subjective concern related to anesthesia was the fear of not regaining consciousness, followed by concerns about postoperative pain, intraoperative emergence, and other issues. Conclusions: This study confirms that being female is a significant risk factor for preoperative anxiety. Therefore, it is necessary to provide enhanced preoperative anxiolytic therapies, including preoperative patient education and other interventions, to individuals undergoing surgical procedures.