This study aimed to investigate the relationship among crisis in adolescents interpersonal relationships, suicidal ideation, and hope, and verify the mediating effects of hope in the relationship between crisis in adolescents interpersonal relationships and suicidal ideation. According to the study purpose, adolescents from a high school located in Gyeonggi-do were recruited for a survey, and 474 students were used for the final analysis. For all analyses, SPSS 23.0 program was employed. Major results of this study can be summarized as follows. First, crisis in adolescents interpersonal relationships had positive correlation with suicidal ideation and negative correlation with the sub-factors of hope such as agency thinking and pathways thinking, agency thinking and pathways thinking showed negative correlation with suicidal ideation. Second, one of the sub-variables of hope, agency thinking, was confirmed to partially mediate crisis in adolescents interpersonal relationships and suicidal ideation, while pathways thinking showed insignificant mediating effect.