This study examines the impact of High-Performance Work Systems (HPWS) on industrial safety through the lens of organizational paradox theory. HPWS has a dual nature: it enhances employee capabilities and motivation to improve organizational performance, yet simultaneously creates safety risks through intensified performance pressures. We propose that these paradoxical effects of HPWS can be managed through labor unions. Using the Korea Labor Institute's Workplace Panel Survey (WPS) spanning 2015 to 2021 (N=1,584), we empirically test hypotheses. The results demonstrate that in establishments without unions, HPWS significantly elevates workplace injury rates. In unionized workplaces, however, the relationship between HPWS and injury rates proved non-significant, with labor-management relations serving as a crucial moderating factor; establishments with higher cooperative labor relationships showed that HPWS significantly reduces accident rates. Our findings suggest that building a cooperative climate between labor and management can enhance the strategic effectiveness of HPWS systems, reconciling the tension between performance demands and employee safety concerns.