A radar apparatus (100) for detecting around a ship is provided. The apparatus (100) includes an unstable area detecting module (10) configured to observe a variation in a signal level corresponding to detection data over a plurality of scans, obtain unstableness of the observed detection data, and detect unstable areas (41, 42, 43, 44, 410, 420, 430, 440) based on the unstableness, a determining module (22) configured to measure a size of each of the areas and determine the area as a small target object area (41, 43) when the size of the area is below a given threshold, a processing module (6) configured to process the detection data corresponding to the small target object area (41, 43) to be emphasized when displayed, than the detection data corresponding to the other unstable area (42, 44), and a display unit (8) configured to display the processing result.