The purpose of the present invention is to achieve a particle beam therapy device provided with a beam adjustment device that supports the adjustment of a beam axis. This particle beam therapy device (100) is provided with a beam adjustment device (18) that supports the adjustment of a beam axis, which is an axis in the propagation direction of a charged particle beam (44) when the charged particle beam is not scanned by scanning electromagnets (25x, 25y), in a particle beam irradiation device (4). The beam adjustment device (18) is provided with a beam adjustment calculator (17) which calculates the values of excitation currents of two x-direction steering electromagnets (23a, 23c) and two y-direction steering electromagnets (23b, 23d) so that the beam position of the charged particle beam (44) on a first screen monitor (30), disposed to be movable in a direction crossing the beam axis at the downstream side of the scanning electromagnets (25x, 25y), and on a second screen monitor (31), disposed detachably on a tip part (snort (39)) of the particle beam irradiation device (4), is present on a reference beam trajectory (45) passing through an isocenter (48).Lobjet de la présente invention est dobtenir un dispositif de radiothérapie à base de faisceau de particules comprenant un dispositif de réglage de faisceau qui supporte le réglage dun axe de faisceau. Ce dispositif de radiothérapie (100) à base de faisceau de particules comprend un dispositif (18) de réglage de faisceau qui supporte le réglage dun axe de faisceau, qui est un axe dans la direction de propagation dun faisceau de particules chargées (44) lorsque le faisceau de particules chargées nest pas balayé par des électroaimants de balayage (25x, 25y), dans un dispositif dexposition (4) à un rayonnement dun faisceau de particules. Le dispositif (18) de réglage de faisceau est pourvu dun calculateur (17) de réglage de faisceau qui calcule les valeurs de courants dexcitation de deux électroaimants dorientation
