Disclosed is a device for detecting orientation of a radioactive material to determine presence and position of the radioactive material, comprising: at least one first radiation detector; at least one second radiation detector, each of said at least one second radiation detector and each of said at least one first radiation detector being arranged side by side and in pairs, detection surfaces of said first and second radiation detector being in the same plane to receive radiation from the same direction in the same manner and to generate a first detection signal and a second detection signal, respectively; a shielding plate, said shielding plate being arranged between said first radiation detector and said second radiation detector arranged in a pair and extending forward beyond said detection surfaces; and a determination device for receiving the first and second detection signals from said first and second radiation detector, and determining whether a radioactive material exists or not according to said first and second detection signals and simultaneously determining the orientation of the radioactive material according to the difference between said first detection signal and said second detection signal. Also disclosed is a method for detecting orientation of a radioactive material.