For this purpose, a radiation-irradiation device (1) includes a leg unit (10), a radiation source unit (40), an arm unit (30) that supports the radiation source unit, a body unit (20) that is an arm support unit supporting the arm unit (30), and a raising/lowering mechanism (50) that raises and lowers the arm unit (30) relative to the body unit (20). The arm unit (30) includes a first arm (31) that is connected to the radiation source unit (40), a second arm (32), a first rotational moving portion (33) that connects the first arm (31) to the second arm (32) so as to allow the first and second arms (31, 32) to be rotationally movable relative to each other, and a second rotational moving portion (34) that connects the second arm (32) to the raising/lowering mechanism (50) so as to allow the second arm (32) to be rotationally movable relative to the raising/lowering mechanism (50). The rotation of the second arm (32) from an initial rotational movement position, which is performed using the second rotational moving portion (34), is regulated by the body unit (20) in a case in which the arm unit (30) is positioned at a position other than a first position where the arm unit (30) is raised or lowered by the raising/lowering mechanism (50).
