This paper describes an example application of Thermo Active Building System (TABS) in a publishing company headquarters building located in the urban area of Tokyo, Japan. The successful integration of architectural, structural and building services design made it possible for this technology to be implemented. Since a part of the structure is utilised as a radiant surface instead of mounting ceiling panels, the floor height was greatly reduced. Some of the most important features of the novel TABS implemented in this building are the alternately arranged nomal and reversed beams, which form a concave-convex salb structure. The bottom surface of the concave slab and beam structure works as a radiant surface for the lowerfloor, while the ho space works as a passage for supply air for the upperfloor. On the other band, the hollow space in the convex structure works as a passage for return air and smoke exhaust from the lowerfloor. This means that all the space formed by slabs and beams are utilised for the building services. In addition, the building structure is effectively utilised as a radiant surface with a large heat storage capacity reducting electricity demands during the peak period Furthermore, indoor temperature variation could be made smaller. In addition to the essential points of TABS, this paper reports the results of a mockup experiment of the radiant cooling and heating system during the construction phase, and the results of the heat balance in a room. Moreover, it re the results of a questionnaire distributed to occupants to investigate the indoor environment after the commencement of operation.