An objective of this invention is to shorten the obtaining cycle for a charged particle beam irradiation position even in the case where radiations, emitted along with the irradiation of a charged particle beam, provide an effect. A beam position monitor (30) is provided with a plurality of position monitors (4) and a beam data processing device (11) that performs calculation processing of the state of a charged particle beam (1), based on a plurality of signals outputted from the position monitors. The beam data processing device (11) includes a plurality of channel data conversion units (21) that perform AD conversion processing of the plurality of signals outputted from the position monitors (4)； a position size processing unit (23), for each of the position monitors (4), that calculates the beam position of the beam (1), based on voltage information obtained through the AD conversion processing； and an integrated control unit (40) that controls the plurality of channel data conversion units (21) in such a way that while the beam (1) is irradiated onto an irradiation subject (15), AD conversion processing of the signals is performed at different timings for the respective position monitors (4).本發明提供一種射束位置監視裝置及粒子線治療裝置，其目的在於即便是在有伴隨帶電粒子射束之照射而產生的放射線之影響的情況下，仍可縮短帶電粒子射束之照射位置的取得間隔。射束位置監視裝置(30)，係包括：複數個位置監視器(4)；以及根據從此等位置監視器(4)輸出之複數個信號來運算處理帶電粒子射束(1)之狀態的射束資料處理裝置(11)，而射束資料處理裝置(11)係具有複數個通道資料轉換部(21)，其係執行從位置監視器(4)輸出之複數個信號的AD轉換處理；且依每一位置監視器(4)具有位置尺寸處理部(23)，其係根據經AD轉換處理過的電壓資訊來計算射束(1)之射束位置；以及具有總括控制部(40)，其係在射束(1)照射於照射對象(15)之期間，以依對應複數個信號的每一位置監視器(4)錯開時序而執行AD轉換處理之方式，來控制複數個通道資料轉換部(21)。
