In radiotherapy, bolus is used for the superficial tumor, but there in limitation in the dose distribution control. Therefore, the changes in the dose distribution according to the application of the magnetic bolus are to be evaluated. In the case of not applying the bolus, and in applications of the magnetic bolus and the non-magnetic bolus, OSLD (Optically Stimulated Luminescence Dosimeter) was used to measure the dosage for each depth for comparison. In the case of not applying the bolus and applying the non-magnetic bolus, the difference according to the depth correction was a maximum of 2.17%, and the difference according to applying the nonmagnetic bolus and the magnetic bolus was a maximum of 4.39 %. In addition, the changes in the dose value according to the application of magnetic bolus showed average increase of 2.39 from the surface to 7 mm, and there was average decrease of 0.43% in the depth of 8 cm-15 cm. Therefore, in the radiotherapy, it is considered that the increase in therapeutic effect and normal organ protective effect can be expected according to the application of the magnetic bolus.