PROBLEM TO BE SOLVED: To intuitively grasp the arrangement position and detailed data of each trap. SOLUTION: On a screen is displayed a piping diagram 20 in a plant and on this piping diagram 20 are displayed icons 21 to 25 corresponding to each trap. Then, when any one of these icons 21 to 25 is double clicked on, a display window 35 is displayed on the screen and in this display window 35 is displayed detailed data of the trap corresponding to the icon double clicked on.