A navigation system displays different colors on sections of a travel route according to traffic density. A method for controlling a traffic information display in the navigation system includes the steps of: if a traveling route is received from a user of a moving object, displaying and guiding a corresponding travel route; determining whether or not traffic density information is requested during travel of the moving object; if the traffic density information is requested, receiving the traffic density information of the travel route from a traffic information center and searching for a predetermined color stored in a storage unit based on the received traffic density information; and displaying the predetermined color on the corresponding section of the travel route.