<p>Individuals who ruminate are likely to exhibit behavioral inactivation. In this study, we explored this mechanism by focusing on the processing mode theory, which divides thought style into two modes: abstract and analytic thought (AAT) and concrete and experiential thought (CET). Based on the existing rumination theories, we focused on the difference in the effect of processing modes on behavioral activation according to the level of dysphoria. We conducted a one-year longitudinal survey with 1,030 Japanese adults at five measurement points. We measured processing modes and behavioral activations using questionnaires and analyzed within-person bidirectional associations using a random intercept cross-lagged panel model. The results showed that AAT predicted subsequent increases in avoidance behaviors in the group with high level of dysphoria, but not in that without it. Our findings suggest that individuals with high level of dysphoric moods may amplify their avoidance behaviors by increasing their AAT. Therefore, practitioners may target reducing AAT to improve behavioral inactivation.</p>