Purpose: The radiation therapy is often followed by neurosurgery including cranial reconstruction, in which titanium plates are used. Thus, it was investigated whether titanium plates for skull reconstruction may affect the dose. Materials and Method: A titanium plate was placed in a phantom with 160 mm in depth and the doses were measured after unidirectional irradiation and/or opposing portal irradiation by the chamber method and film method. Results: Dose changes with the plate in unidirectional irradiation were －0.9% , ＋6.6% , ＋1.4% and 0% at 0 mm, 10 mm, 15 mm and 80 mm from the surface of irradiation side, respectively. Changes in dose towards the center ranged from ＋3.5 to －2.1% . Conclusion: Changes in radiation dose from use of a titanium plate in cranial reconstruction were within a range that would not affect post-operative radiation therapy.