Abstract: Provided is a tag system for providing status data of a device, which provides status data of a device using a uniform resource locator (URL) through a tag to a terminal and allows the terminal to provide the status data of a device in the form of a web browser in conjunction with a web server. According to the present invention, data of a device can be immediately checked through a mobile terminal without installing a dedicated application. Particularly, in the case of a device lacking a network or monitoring function, such a device can operate as an Internet of things (IoT) device via a terminal by applying a tag according to the present invention. Through application of the present invention, the remaining amount of a replaceable battery used for a drone, a camera, or the like or an auxiliary battery used for a smartphone can be measured, and a status of a control device installed in a production facility lacking a monitoring system can be checked on the spot.