A CPU 11 of a boundary line detection device 10 according to an embodiment of the present invention is configured to function as an image acquisition component 112 that acquires images captured (inputted) via an image input device (a camera or the like), captured images received via a network, and so forth, and a boundary line detector 114 that detects a boundary line included in these captured images. The boundary line detector 114 is configured to specify, using a learned model 152, a plurality of estimated points estimated to be points on a boundary line included in a captured image and to detect the boundary line included in the captured image on the basis of at least the specified estimated points.