In this paper, we describe a robotic ultrasound (US) probe scanning system for reducing the manual tasks of US technicians and assisting in interventional procedures. The system consists of a probe scanning robot that uses McKibben artificial muscles, an optical tracking device, and in-house software for volume reconstruction and automatic guidance of surgical tools. The proposed system is lightweight and safe due to the use of artificial muscles, and allows positional control of the B-scan plane through transformation of US calibration. We applied the robotic system to robotic three-dimensional (3D) ultrasound and automatic ultrasound guidance. To clarify the system’s feasibility, we performed phantom and human liver volume reconstructions, as well as needle guidance. The volume qualities of the reconstruction were validated by cross-correlation with reference echograms and reslicing of the reconstructed volumes. The correlation values were 0.80 ± 0.06 for the phantom and 0.53 ± 0.06 for the human liver. Regarding needle guidance, we confirmed that the B-scan plane automatically followed the needle. The translation error was −0.10 ± 1.26 mm and rotation error was −0.22 ± 1.81 degrees. Analysis of frequency response confirmed that the system was able to stably follow a motion at frequencies less than 0.3 Hz. The experimental results demonstrate that the robotic probe scanning system has great potential for yielding acceptable 3D volumes using two-dimensional (2D) ultrasound and assisting interventional procedures under US guidance.