A surgical robot system for stereotactic surgery, according to the present disclosure, may include: a stereotactic surgery unit to move and rotate a surgical instrument; a controller to receive the first imaging data that represents a three-dimensional image of a surgical portion that includes a surgical target; one or more markers to be attached to, or disposed near, the surgical portion; an imaging unit to create the second imaging data that represents a three-dimensional external image of the surgical portion; and a tracking unit to track the positions and postures of the imaging unit and the markers. The controller may create the coordinate conversion relationships for converting a coordinate from the first coordinate system of the first imaging data into the fourth coordinate system of the stereotactic surgery unit and control the stereotactic surgery unit by using the coordinate conversion relationships above.