A mobile radiation generator includes an arm part on which an irradiation section is mounted. The height of the irradiation section is changed in a case in which the arm part is rotated. A spring generates negative rotational moment in a negative direction where the irradiation section is displaced upward against positive rotational moment that acts on the arm part in a positive direction due to own weight of the irradiation section and the like. A friction mechanism is built in a pillar. In a case in which the magnitude of the positive rotational moment and the magnitude of the negative rotational moment are different from each other, the friction mechanism generates a frictional force acting in a direction opposite to a direction where the arm part is to be rotated due to a difference between the positive rotational moment and the negative rotational moment and cancelling the difference.
