Abstract: A self-scanning checkout device includes a registration section having a stationary scanner for permitting a customer to input article information for a purchased article, a counter arranged on the downstream side from the registration section in the article moving direction, for receiving a purchased article which has been registered thereon, and a monitoring section for monitoring a movement of the purchased article. The monitoring section sets an article registration flag when information of the purchased article is read by the stationary scanner, checks the article registration flag when the passage of an article is detected by article sensors disposed near and on the downstream side from the reading position of the stationary scanner, resets the article registration flag when the article registration flag is detected to be set, and issues an alarm indicating the passage of an unregistered article when the article registration flag is detected to be reset.