Cyber Knife Radiotherapy is used to treat tumors located in unmovable organs such as brain and also abdominal tissues which have a small range of movements. In general, any movements of the prostate is natural; however, in treating prostate tumors with Cyber Knife therapy, especially with high doses, it is dangerous for normal parts of prostate itself as well as surrounding healthy tissues. The aim of this study was to estimate the amount of the delivered radiation doses in the cancerous tumor of the prostate, its surrounding tissues and structures during various prostate movements throughout the treatment process. To achieve such a goal, Monte Carlo method and MCNPX code was applied. The prostate and its surrounding tissues were designed through using simple mathematical phantoms. In this study, the delivered doses of radiation to the prostate as it moved or without any movements were calculated. The results showed that the amount of delivered dose for 10 minutes radiation therapy and without prostate movement was 28 Gy in clinical target volume. The delivered dose to the healthy tissues as prostate shifted 10 mm (moving up and down) during the 10 minutes radiation therapy was calculated 5.64 which was equivalent to 20% out of total dose and the delivered dose to the tumor was determined 80% out of total doses. When up and down prostate movement was traced 15 mm during the 10 minutes radiation therapy, the delivered dose to the healthy tissues was calculated 8.64 Gy which was the equivalent to 30% out of the total dose and the delivered dose to the tumor was determined 70% out of the total dose. When the prostate shifted 5 mm in left and right direction during the 10 minutes radiation therapy, the delivered dose to the healthy parts is figured 2.8Gy that is the same as 10% out of total doses. Also the delivered dose to the tumor was 90% out of total doses. According to the results, the highest rate of the delivered dose to the healthy tissues was at the time when the prostate shifted 15 mm in up and down direction. Furthermore using an automatic tracer system with as low delay as possible in Cyber Knife Radiotherapy is necessary to achieve the effective treatment.