Provided is a service system for providing context information based on a ubiquitous sensor network and a method thereof. The context information providing service system includes: a sensing block for collecting context information of each user; an intermediating block for changing the user context information transmitted from the sensing block into a request to store the request in a context recognizing block, transmitting the request to the context recognizing block, and transmitting a service request to the context recognizing block; and a context recognizing block for storing context information of each user according to a context information storing request transmitted from the intermediating block, and providing a relevant service by using the user context information.