Many appliances include computers, such as home electrical appliances, A/V appliances and cellular phones. If these computers can obtain the user context by themselves, they will be able to automatically offer suitable services to the user appropriate for the user context. The appliances must use sensors to recognise the user context. Here, we developed a sensor device that provides sensing function to appliances to allow recognition of the user context. The sensor device is called "UDSS (Ubiquitous Data Source Server)." This sensor device has five sensors: temperature, humidity, sound, light and pyroelectric infrared sensors. UDSS provides the current sensed value of each sensor. In addition, UDSS can notify the changes in the pyroelectric infrared sensor value to subscribing appliances. These functions are implemented using UPnP, which allows the appliances in a home network to use this sensor device easily.