PROBLEM TO BE SOLVED: To provide an X-ray diagnostic apparatus which reduces time lag in photography (fluoroscopy) after an in-use detector is exchanged from a later-stage detector to a former-stage detector.SOLUTION: An X-ray diagnostic apparatus 1 includes: an X-ray tube 21； a later-stage detector 31a； a former-stage detector 31b the maximum visual field size of which is smaller than the maximum visual field size N of the later-stage detector 31a, and which can detect X-rays at a set position former than the later-stage detector 31a； and position control means 134 for disposing the former-stage detector 31b so that [1] the former-stage detector 31b is located outside a first irradiation area XM and [2] at least part of the former-stage detector 31b is located within a second irradiation area XN, when detecting X-rays in a visual field size M smaller than the maximum visual field size N of the later-stage detector 31a during using the later-stage detector 31a.【課題】Ｘ線診断装置において、使用検出器が後段検出器から前段検出器に切り替えられた後の撮影（透視）のタイムラグを減少させること。【解決手段】Ｘ線診断装置１は、Ｘ線管２１と、後段検出器３１ａと、最大視野サイズが後段検出器３１ａの最大視野サイズＮより小さく後段検出器３１ａより前段のセットポジションでＸ線を検出可能な前段検出器３１ｂと、後段検出器３１ａを使用中に後段検出器３１ａの最大視野サイズＮより小さい視野サイズＭでＸ線を検出する場合に、［１］前段検出器３１ｂが第１照射領域ＸＭ外の位置、［２］前段検出器３１ｂの少なくとも一部が第２照射領域ＸＮ内の位置、となるように、前段検出器３１ｂを配置する位置制御手段１３４と、を有する。【選択図】 図７
