Abstract: A radiation scanning mechanism is capable of increasing an observable range by eliminating a restriction on a scannable range of a conventional scanning mechanism for a radiation TV set for scanning an observation object by a directional radiation detector to display the distribution state of a radioactive material as an image. In the radiation scanning mechanism, an inner frame having a rotary shaft provided with a directional gamma-ray detector is attached to an outer frame having a rotary shaft so that the rotary shaft of the inner frame may perpendicularly and rotatably intersect the rotary shaft of the outer frame, and the rotary shaft of tile outer frame is rotatably supported by an outer frame support base.