Abstract: In a network management system, information items respectively of connection relationships, containment relationships, and display priority of a plurality of managed object instances (resources) are stored in a memory. According to a predetermined algorithm, there is calculated an evaluated value for display for each of the instances depending on the containment relationship information and display priority to select a limited number of instances representable on a screen. Displayed on the screen is a network layout diagram including icons representing the plural instances thus selected. When the user specifies one of the icons, the specified instance and a number of representable instances selected according to the evaluated values from a group of instances under the specified instance in the containment relationships are displayed in a new network layout diagram on the screen.