Purpose: Adolescent suicide is an important issue worldwide. Although literature on preventing suicide among adolescents tends to focus on suicidal ideation, suicidal planning is also an important issue as a stage leading to suicidal behavior. This study aims to identify suicidal planning-related factors, including generalized anxiety disorder, among adolescents who had suicidal ideation. Methods: This secondary study used data generated from the 16th(2020) Korea Youth Risk Behavior Web-based Survey, which included 5,979 students who had suicidal ideation. Factors related to suicidal planning were identified by performing a logistic regression analysis of the participants. All analyses were performed using SPSS 27.0. Results: Among adolescents who had suicidal ideation, 23.8% had suicide plans. The suicidal plans were significantly related to school level (middle, OR=1.38, 95% CI=1.22~1.55), whether they were living with family (no, OR=1.36, 95% CI=1.06~1.75), perceived body image (normal, OR=1.23, 95% CI=1.05~1.44; Obese, OR=1.33, 95% CI=1.14~1.54), depression (yes, OR=1.47, 95% CI=1.25~1.72), tobacco use (yes, OR=1.31, 95% CI=1.12~1.54), alcohol use (yes, OR=1.21, 95% CI=1.06~1.38), drug use (yes, OR=1.96, 95% CI=1.44~2.66), and/or generalized anxiety disorder (severe, OR=1.76, 95% CI=1.44~2.14). Conclusion: The findings of the study suggest that in addition to the commonly recognized factors for adolescent suicide, generalized anxiety disorder should also be considered when establishing strategies to prevent suicide planning in adolescents who had suicidal ideation.