A technique for reliably changing settings according to the usage environment to increasingly ensure a high-security network connection environment. A PC judges the usage environment of the PC by searching for addresses of nearby devices such as Bluetooth devices and, depending on the usage environment, automatically changes the security level setting. Even when the PC is in a usage environment in which the security level should be "home" or "office" but any devices that should be in that usage environment are not detected during usage environment judgment processing, the level is set to the "mobile" security level at which high security is ensured.