The growth of the ubiquitous computing and the Web computing is expected to make the internet society more convenient. Furthermore, intelligence of information systems is also expected to make our society safer and more content. The symbiotic computing is a technology to introduce symbiotic relations between users and computing systems by installing a function to recognize the important and relevant aspects in the real space into computing systems, using Ubiquitous computing and Web computing. We have developed various symbiotic applications that have practical use in our society, based on the concept of the symbiotic computing. In this paper, we propose a design of cognitive agents to enhance the cognitive function for symbiotic applications to recognize the real space. We call this cognitive agent as symbiotic agent which is included in our proposed symbiotic functions to establish symbiotic computing.