Percutaneous coronary intervention (PCI) for anomalous left coronary artery (LCA) originating from the noncoronary cusp (NCC) is challenging, as it poses difficulties with the engagement of the guiding catheter and the establishment of backup support. This report examines the case of a 69-year-old woman with unstable angina of anomalous LCA origin. The computed tomography showed a diffuse plaque in the middle of the left anterior descending (LAD) artery and an anomalous LCA originating from the NCC. After successful engagement of a straightened Judkins-Left diagnostic catheter, the angiography revealed a diffuse plaque in the middle of the LAD artery. We then engaged a Judkins-Right guiding catheter. Due to the weak backup support of the guiding catheter, we used another wire to stabilize it, and the stent was then implanted successfully. To our knowledge, this is the first case report of PCI for an anomalous LCA originating from the NCC.