Blood circulatory system is very complicated and its shape depend on individual, which might affect cardiac and/or cerebrovascular diseases in near future. This report presents prototype imaging system for in vivo carotid artery using ultrasound B-mode images. Then, we try to simulate blood flow about mathematical model and real carotid artery shaped model with branched flow. One of a final goal is to establish a new imaging system for examination of existence or nonexistence about plaque and infarction including its shape at inner wall of blood vessel, furthermore to establish simulation technique for real artery shape with heartbeat.