During coronary angiography of right coronary artery (RCA), a catheter wedged into a conus artery, and a remarkable coved-type ST elevation was seen in precordial lead through V1-3. LCA angiography did not show any abnormal findings, but we recognized a slow contrast flow in a conus artery by RCA angiography. The patient was free from chest pain, and a ST elevation was improved. The slow flow of a conus artery was recovered within five minutes. Precordial ST elevation may be caused by a catheter-induced spasm of a conus artery.