To provide a POS system allowing a salesperson to prevent theft in a salesroom while selling.

This POS system comprises input means 62, 64, 66 for inputting merchandise sales data, and output means 40 for outputting and displaying the sales data on a monitor 50, so that it collects and records data accompanying merchandise sales and relating to sales management at the point of sales. The POS system further comprises a single or a plurality of cameras 20 for photographing moving images of a merchandise salesroom, and conversion means 30 for receiving signals of the moving images photographed by the camera(s) 20 and converting the same into digital image signals. The output means 40 outputs and displays the sales data inputted by the input means 62, 64, 66 and the digital image signals converted by the conversion means 30 together on the monitor 50.