To provide a control system capable of automatically switching web images of a line information terminal device in accordance with abnormality, etc., that occurs in a production line.

When a programmable logic controller 2 detects that an event occurs in the production line 1, the programmable logic controller 2 stores data of event information preassociated with the event that occurs. When a line indicator (line information terminal device) 3 reads the data of the event information from the programmable logic controller 2, a URL is acquired on the basis of the data of the event information and data of a web image designated by the acquired URL area read from a web server 6.