A particle beam treatment apparatus including a rotating gantry that revolves and displaces an irradiation port for irradiating a radiation treatment room provided inside of the rotating gantry with a charged particle beam comprises: a gantry body portion forming the rotating gantry a mounted magnet a displacement meter or an acceleration meter and a control mechanism. The mounted magnet is connected to the gantry body portion with an intermediation of a magnet support, and guides the charged particle beam to the irradiation port. The displacement meter or the acceleration meter is provided to the mounted magnet, and measures a displacement or an acceleration of the mounted magnet. The control mechanism controls a position of the mounted magnet in a direction so as to reduce the displacement or the acceleration with at least a single degree of freedom measured by the displacement meter or the acceleration meter.
