PURPOSE: To facilitate maintenance by providing a means of measuring the radiation intensity of a transportation system, a means of detecting the operation state of an actuator regarding transportation, and a means of discriminating whether the transpotation of a radioactive material is normal or not.

CONSTITUTION: A device for detecting transporation abnormality of the radioactive material is equipped with a radiation measuring instrument 11 and a blocking detector 12. When a valve 3 is opened to allow radioactive powder 1 to fall by its weight, the blocking detector 12 shows a gradual decrease in radiation intensity if the powder 1 falls, but no decrease in radiation intensity if the powder 1 falls, but no decrease in radiation intensity if the powder 1 does not fall and is blocked in a powder vessel 2. When the valve 3 is opened, a timer is actuated and a switch is closed at reference time to compare the radiation intensity with reference intensity. In this invention, the radiation measuring instrument 11 does not contacts the radioactive powder, so the maintenance is facilitated.