The alarm device includes an acquisition part, an alarm judging part, a notification part, a static extraction part, a shielding boundary setting part, and a suppression part. The acquisition part acquires reflection point information and object information. The alarm judging part determines whether the object is an alarm candidate for each of the objects. The notification part issues a notification regarding the alarm candidates. The static extraction part extracts static reflection points. The shielding boundary setting part sets an approximate straight line as a shielding boundary by robust estimation. The suppression part suppresses notification of alarm candidates that are on the opposite side of the shielding boundary.