The sensors in a ubiquitous network are limited because of the low electricity and because they are ultra light, so many studies have revolved around the sensor. This study suggests a way to improve the registration and authorization processes of a sensor node based on an alias for privacy. We introduce RA(Relay Agent) for the restrict function of sensor node, and improve anonymity for private information of each sensor node by assigning alias from SM(Service Manager) in procedure of registration and authentication. The private information in each sensor node should be secured during every procedure. In the results of the analysis, safe communication between nodes was guaranteed with the only partial increment of computation power of RA and SM without an increase in the amount of sensor nodes. * Keywords: Ubiquitous Network, Privacy, Anonymity, Security, Low-Power Sensor Node, Alias