We started the project of the surgical robotic system in 2001 as an application for abdominal surgery. The robot enables a surgeon to perform various surgical procedures in abdominal region as in open surgery. We have extended the concept of the robotic surgery system and developed a new robotic system for cardiac and endovascular surgery. The new robot has a stereo video camera system, two manipulators and a flexible tube, 3 mm in diameter, used as an instrument channel. The maximum diameter of the robot is 6 mm. We also applied 4D ultrasound imaging system to the robot system, that enabled to observe a situation of the robot and surgical field in a blood flow. In this paper, we describe a detail of the robot system and results of phantom experiment.