The purpose of the invention is to provide a transcranial magnetic stimulation system capable of guiding a patient into an optimum posture for treatment. The system 1 of the invention includes an optical device 502 for projecting a light spot 805 to a head of a patient and detecting a reflection light of the light spot; a memory means 71 for memorizing information included in the reflection light detected by the optical device as a reference information when the projected light spot on the patient overlaps a marking (800) provided on the patient; a calculation means 72 for using the reference information memorized in the memory means and a comparison information included in the reflection light of the light spot to calculate an overlap ratio between the marking and the light spot corresponding to the comparison information; and a display means 504 for displaying the overlap ratio.