Introduction. In Korea, the number one cause of death among adolescents aged 10 to 19 is suicide (intentional self-harm), which is gradually increasing. This suggests that efforts to identify the causes of suicide and provide educational and counseling interventions to resolve it should continue. This study aims to suggest ways to alleviate the effect of adolescent depression on suicidal thoughts through gratitude and mindfulness. Study participants and methods. The research subjects were 609 intentionally sampled Korean middle and high school students. The survey subjects were 58.9% male, 41.1% female, 49.0% middle school students, and 51.0% high school students. As for residence, 80.7% lived in small and medium-sized cities, followed by 17.2% in rural areas. Data were collected through the survey method and analyzed using SPSS PC+ Win. Ver. 26 and PROCESS macro ver. 4.2. The statistical methods applied to the analysis are frequency analysis, reliability analysis, correlation analysis, and conditional direct effect analysis. Results. First, as a result of correlation analysis, depression showed a negative correlation with mindfulness (r=-.501, p<.01) and gratitude (r=-.403, p<.01) and a positive correlation with suicidal ideation. (r=.666, p<.01). Mindfulness showed a positive correlation with gratitude (r=.423, p<.01) and a negative correlation with suicidal ideation (r=-.318, p<.01). Second, depression had a significant negative effect on gratitude, and gratitude had a significant negative effect on suicidal ideation. The indirect effect of gratitude was significant as there was no zero between the lower and upper bounds of the bootstrap, and it played a mediating role. Third, the conditional direct effect was significant in all three conditions of mindfulness. As mindfulness increased, the positive effect of depression on suicidal ideation decreased, so mindfulness played a buffering role. It was confirmed that the effect of depression on suicidal ideation was reduced by intervening with mindfulness and gratitude in adolescents with high levels of depression. Practical significance. These results can be used as important data for schools and counseling organizations to provide counseling to adolescents with high levels of suicidal thoughts due to depression.