Recently, we developed an evaluation system for three-dimensional (3D) visuo-motor control in a virtual reality (VR) environment. The proposed system enabled us to analyze circular tracking movements in VR space with millimeter level accuracy. In this study, we analyzed the effect of depth information in the 3D visuo-motor control based spatial parameters in Cartesian coordinate. Six healthy human subjects participated in this study, and performed circular tracking movements of a target rotating at 0.125Hz in three different planes (ROT(0), ROT(45), ROT(90)) of the 3D space. We used spatial errors in Cartesian coordinate to analyze the accuracy of tracking movements. As a result, we found that the 3D error for the circular tracking movement in the ROT(0) and the ROT(45) planes were significantly larger than that in the ROT(90) plane. This is because the error of the Z axis indicating the depth was remarkably increased in the circular tracking movement of the ROT(90). The result means that the depth information is an important control metric for visuo-motor control in 3D space. Consequently, the experimental protocol and data analysis in this study allowed us to spatially analyze the motor control characteristic for circular tracking movement with various depths in 3D VR space.