This paper reports on the magnetic propulsion of a spiral-type endoscopic mircorobot in a real small intestine. Magnetic modeling was carried out to design and commission an external electromagnetic system, which wirelessly provides power to the robotic agent. The capsules with different spiral structures were magnetically propelled inside a segment of porcine small intestine. From the results, it is shown that the propulsive velocities of the tested capsules are in the range of 2.5 ~ 35 mm/s when rotating frequencies varying between 1 ~ 5 Hz are applied. Among all the capsules prepared for this study, the capsule No. 5, with one spiral and a helical angle of 20° and spiral height of 1 mm, shows the best performance. The effects of the spiral parameters, such as helical angle, number of spirals and spiral height, are evaluated by using the propulsion velocity and the slip ratio as the evaluation criteria.