A particle beam treatment apparatus includes: a rotating gantry configured to axially rotate in a state where a bed fixed to a stationary system is disposed inside the rotating gantry and an irradiation port of a beam is fixed to a body of the rotating gantry； a tunnel structure configured to have at least a horizontal floor surface and have an internal space in which at least a part of the bed is accommodated； and a rotation supporter configured to cause the tunnel structure to be stationary in the stationary system independently of axis rotation of the rotating gantry by rotationally displacing the tunnel structure with respect to an inner side surface of the rotating gantry.
