A check-out device includes a scanner (11) for reading an article code fixed to an article, an entry conveyor (21) for conveying the article after reading the article code a weigh scale (22) for measuring weight of an article on the entry conveyor to produce measured weight data a RAM (313) for storing article data of various articles, each article data including an article code and reference weight data, and a processing unit (311, 312, 29, 23, 12) for obtaining from the RAM the reference weight data of the article corresponding to the article code, comparing the obtained reference weight data with the measurement weight data, and performing a sales processing for the article whose article code is read by the scanner (11) after confirming that the article whose article code is read is identical to the article on the conveyor. The processing unit includes a controller for allowing an operation of the conveyor after confirming that the articles are identical to each other.