We examined the effects of attachment security priming on economic risky decisions and their neural underpinnings. Participants were exposed to either attachment security primes (N = 28) or control primes (N = 29) and then completed a gambling task while connected to an electroencephalogram system. We anticipated that attachment security priming would affect risky decision-making at both the behavioral and neural levels. Feedback-related negativity (FRN) and P3 components were analyzed. At the behavioral level, participants in the attachment security priming group selected less risky choices than those in the control group. At the neural level, participants exposed to attachment security primes exhibited attenuated FRN but no significant difference in P3 amplitude. The regression analysis showed that small P3 amplitude predicted large risk-taking tendencies in the control priming group, whereas P3 amplitude did not significantly predict risk-taking tendencies in the attachment security priming group. These findings suggest how boosted attachment security affects economic risky decisions: It lowers people's affective reactions to undesirable outcomes and buffers people's underestimation of the outcome salience. Specifically, attachment security seems to attenuate risk-taking by preventing people from down playing the significance of outcomes. Our findings extend existing knowledge by demonstrating attachment security priming ability to reduce risk-taking tendencies beyond naturalistic to economic decisions.