PROBLEM TO BE SOLVED: To obtain a breast image having an optimum density with a reduced burden on the subject.SOLUTION: This mammography apparatus includes a radiation irradiation section 3 and a photographing table 4 connected to each other by an arm so that they face each other, and the breast M compressed onto photographing table 4 using a compression paddle 7 is imaged by rotating the arm according to the imaging direction. In the apparatus, the size of the breast M is detected, and the position of a dose detector 20 is moved along the side of the photographing table 4 facing the chest wall of the subject according to the detected size of the breast M and the angle of rotation &theta of the arm when the arm is moved in rotation.COPYRIGHT: (C)2010,JPO&INPIT【課題】被検者の負担を少なくして最適な濃度の乳房画像を取得する。【解決手段】放射線照射部3と撮影台4とを対向するようにアームで連結し、撮影台4上で圧迫板7を用いて圧迫した乳房Mを、撮影する方向に応じて前記アームを回転させて撮影する乳房画像撮影装置で、被検者の乳房Mのサイズを検出して、検出した乳房Mのサイズとアームを回転移動させた回転角θに応じて、線量検出器20の位置を撮影台4の胸壁に対向する辺に沿って変更する。【選択図】図8