Radial artery puncture is an invasive procedure that frequently used for arterial blood gas analysis or radial artery cannulation. Although known to be safe, less than 0.1% of patients might suffer from severe complication such as finger necrosis. The purpose of this case report is to share the treatment course of finger necrosis after accidental radial artery puncture and to review existing references. Previously healthy, 63-year-old female visited ER with complaints of Left 2nd finger pain and change of skin color after having IV access around her wrist for a procedural sedation. She said that she felt extreme pain after vein puncture. She still felt pain on her 2nd finger after removal of IV access. Her doctor prescribed pain killer and sent her back home. After hospital discharge, she felt more severe pain of her 2nd finger. And her finger started to show bluish discoloration. 12 hours after vessel puncture, she visited our emergency room. Emergency angiography showed a pseudoaneurysm on her left radial artery. The flow of palmar digital artery was intact. However, there was no sign of blood flow from proper palmar digital artery. So, we concluded that the symptom was caused by thromboembolic occlusion of her left radial artery. It was impossible to conduct thromboembolectomy via angiointervention or operation due to extreme embolism formation of distal branch. We tried thrombolysis with using urokinase after entering up to deep palmar arch but it was also failed. Therefore, we decided to perform finger amputation due to gangrenous change of her finger. This case showed that radial artery puncture must be accompanied with collateral flow check-up, carefully conducted procedure and follow-up action and continuous monitoring of digital flow in order to prevent patient from fatal complication.