A surgical robot system includes a slave device having a surgical instrument; and a master device configured to transmit a control signal to the surgical instrument. The slave device includes a guide tube to which the surgical instrument is coupled; and a controller operating the surgical instrument in response to the control signal transmitted from the master device, and operate the guide tube so as to move the surgical instrument to a target position if the target position of the surgical instrument according to the control signal corresponds to a position out of a range of a current working space for the surgical instrument.