The present invention provides a treatment planning apparatus. The apparatus has: a X-RAY image position uncertainty calculation part that predicts a sharpness of a X-RAY image and calculate position uncertainty of affected parts, the sharpness is obtained by a supposed X-RAY strength； a treatment radiation irradiation parameter calculation part that calculates an irradiation parameter of treatment radiation based on the calculated position uncertainty of the affected parts； a X-RAY irradiation dose calculation part that calculates a X-RAY irradiation dose irradiated from X-RAY imaging apparatus to a patient by a supposed X-RAY strength； a treatment radiation dose distribution calculation part that uses the irradiation parameter of the calculated treatment radiation to calculate a dose distribution of treatment radiation irradiated to the patient； a display that displays the calculated X-RAY irradiation dose and the calculated treatment radiation dose distribution.治療計畫裝置係包括：X光圖像位置不確定性演算部，係預測藉由所暫定之X光強度所獲得之X光圖像的清晰度而演算患部的位置不確定性；治療用放射線照射參數演算部，係依據所演算之患部的位置不確定性來演算治療用放射線的照射參數；X光照射量演算部，係演算由X光攝影裝置依據所暫定的X光強度對患者照射之X光照射量；治療用放射線線量分布演算部，係使用所演算之治療用放射線的照射參數，演算照射至患者之治療用放射線的線量分布；以及顯示器，係顯示所演算之X光照射量及所演算之治療用放射線線量分布。
