The present invention relates to a particle beam therapeutic device having a treatment bench (12), an irradiation port (13), rail tracks (14), and a moving floor group (15), wherein the treatment bench (12) is disposed at inner side of a horizontal type cylinder-shaped rotary gantry (11) for placing a patient； the irradiation port (13) is carried by the rotating gantry and rotated along with the rotating gantry around the treatment bench and emit a particle beam toward the treatment bench； the rail tracks (14) are barrel-shaped rails composed of straight parts and arc-shaped parts formed at inner side of the rotating gantry； and a moving floor group (15) are composed of a plurality of moving floor slabs connected in a mutually and freely bendable manner and having driving motors, the moving floor group is moved along the rail tracks by the rotation of the irradiation port. This invention is characterized in that the irradiation port (13) is not connected with the front end parts (29A), (29B) of the moving floor group.粒子線醫療裝置(10)係具有：治療台(12)、照射埠(13)、軌道軌條(14)及移動地板群(15)，治療台(12)是配置於臥式筒狀之旋轉機架(11)的內側且用於載置患者；照射埠(13)，被搭載於前述旋轉機架，與該旋轉機架一起繞前述治療台旋轉並朝向該治療台照射粒子線；軌道軌條(14)，是在前述旋轉機架的內側形成由直線部和圓弧部所構成之桶型的軌道；移動地板群(15)，是由具有驅動馬達(16)且互相可彎曲自如地連結之複數片的移動地板(25)所構成，藉由前述照射埠的旋轉而沿前述軌道軌條移動；其特徵在於，前述照射埠(13)和前移動地板群(15)的端部(29A)、(29B)並未連結。
