Purpose <p>Previous research has identified cognitive factors for suicide (e.g. hopelessness, perceived burdensomeness, and thwarted belongingness), rumination and decentering as influential factors in suicidal ideation. Although it has been suggested that rumination and hopelessness may mediate the relationship between perceived burdensomeness/ thwarted belongingness and suicidal ideation, and decentering may reduce rumination and hopelessness, the underlying mechanisms remain underexplored. This study aimed to examine how cognitive factors influence suicidal ideation through the mediating role of response styles in daily life.</p> Methods <p>Twenty-eight participants (10 males, 17 females, and one identifying as other) completed web-based self-report questionnaires four times per day over seven consecutive days. The surveys assessed cognitive factors, response styles, and suicidal ideation.</p> Results <p>Multilevel structural equation modeling was used to compare models in which perceived burdensomeness, thwarted belongingness, and decentering influenced suicidal ideation either directly or indirectly via rumination and hopelessness. Perceived burdensomeness and thwarted belongingness were found to influence concurrent suicidal ideation partially through rumination. Decentering was associated with reduced rumination. Only hopelessness significantly predicted subsequent suicidal ideation.</p> Conclusions <p>These findings highlight that responses to interpersonal cognitions can induce hopelessness and suicidal ideation, whereas decentering reduces rumination. This suggests that targeting not only cognitive factors but also rumination and decentering may be an effective approach to reducing suicidal ideation in the short term.</p>