An 84-year-old woman was admitted to our hospital because of congestive heart failure, rapid atrial fibrillation, and ischemic heart disease. Percutaneous coronary intervention (PCI) via the left radial artery was performed, and a stent was deployed successfully into left anterior descending coronary artery (LAD). She got into shock state one hour after PCI. Chest X-ray and computed tomography scan revealed increase of soft tissue around the left axilla and implied the existence of hematoma. Hemoglobin level decreased from 13.3 g/dL to 8.2 g/dL and hemorrhagic shock was suspected. Angiography of the left axillary artery demonstrated contrast extravasation, and selective angiography using a micro-catheter identified bleeding from a branch of the superior thoracic artery. Hemostasis was performed successfully by embolization using a gelatin sponge, and improvement of the general condition was obtained. Aberration of 0.025-in. angle tipped guidewire was considered to induce arterial perforation during sheath insertion.