PROBLEM TO BE SOLVED: To provide a treatment beam irradiation object verification device that measures a body condition of a treatment subject easily with little exposure, and can determine whether or not a change in a treatment plan is necessary.SOLUTION: A beam irradiation object verification device 1 includes: an X-ray switching irradiation processing part 6a for irradiating at least two kinds of X-rays from a vertical X-ray irradiation part 13, the energy being switched by an energy switching part 11； a vertical X-ray detection part 14 for detecting the X-ray irradiated from the vertical X-ray irradiation part 13； a pre-treatment verification image creating processing part 7 for creating pre-treatment verification images 20B and 20C based on detection information on the at least two kinds of X-rays acquired by the vertical X-ray detection part 14； a reference image acquisition part 3 for acquiring a reference image 20A acquired at the stage of treatment planning； a comparison processing part 8a for comparing the pre-treatment verification images 20B and 20C with the reference image 20A； and a result output part 4 for outputting a comparison result acquired by the comparison processing part 8a.【課題】低被ばくかつ簡便に、治療対象者の体内状況を測定し、治療計画の変更の要否を判定し得る治療用ビーム照射対象確認装置を提供する。【解決手段】ビーム照射対象確認装置１は、エネルギー切替部１１によって少なくとも２種類のＸ線を垂直Ｘ線照射部１３により照射するＸ線切替照射処理部６ａと、前記垂直Ｘ線照射部１３から照射されたＸ線を検出する垂直Ｘ線検出部１４と、前記垂直Ｘ線検出部１４により取得した少なくとも２種類のＸ線の検出情報に基づいて治療前確認画像２０Ｂ，２０Ｃを作成する治療前確認画像作成処理部７と、治療計画段階で得られた基準画像２０Ａを取得する基準画像取得部３と、前記治療前確認画像２０Ｂ，２０Ｃと前記基準画像２０Ａとを比較する比較処理部８ａと、前記比較処理部８ａにより得られた比較結果を出力する結果出力部４とを有する。【選択図】図１
