1. A detection device, comprising: an image data generation module for generating image data based on echo signals; and a target object detection module for determining an existence of a target object based on a level of the echo signal at each location of the image data for every azimuth; wherein the target object detection module determines a continuity of the echo signals in a distance direction and an azimuth direction for every target object, and outputs an end location for each target object based on a determination result at each location, including a plurality of locations adjacent to a location determined as being a non-target object location.