A radar device is provided that can reliably display sensed image data of an object, regardless of the state of the object (echo) within a sensed range and of the surrounding environment. A behavior data detector 11 generates current level detection data by detecting a level behavior of sensed image data X(n) handled by a W data generator 7 from sensed data x(n) that is output from a sweep memory 4. Previous behavior data constituted by level detection data of several past scans is stored in a behavior data memory 12, and the behavior detector 11 updates the previous behavior data with the current level detection data and outputs the result to the W data generator 7. Detecting characteristics of the sensed image data of corresponding pixels from the behavior data, the W data generator 7 selects filter calculation data W(n), the current sensed image data X(n) or specific filter calculation data Z(n) and outputs the selected result as written image data Y(n).
