We developed a technique for robotic CT-guided out-of-plane needle insertion, and verified its accuracy. In the phantom experiment, we demonstrated that out-of-plane needle insertions performed using the robot were more accurate than manual insertions at the various angles. Furthermore, we succeeded in predicting the movement of the needle movement in vivo, and developed a method to correct the needle displacement in the tissue. In the animal experiment, robotic out-of-plane needle insertions were accurate in the in vivo procedure, particularly with adjustment during insertion.