1. A radar device, comprising: an antenna, from which a detection signal is transmitted while the antenna being rotated and by which a reflective wave of the transmitted detection signal is received to detect echo data, wherein image data is generated based on the detected echo data; a continuity detecting module for detecting a planar continuity of the currently detected echo data with respect to a pixel concerned in the image data; a behavior data generating module for generating behavior data indicative of a behavior of the echo data for a predetermined number of scans of the past in the pixel concerned based on behavior determination data; and an echo kind determining module for determining a kind of the echo data of the pixel concerned based on the planar continuity and the behavior data.