To provide a structure of a plinth not causing a gap between a floor and the plinth and also adaptable to the defect of the floor occurring not only at the time of installation but also in a long period.

A plinth A1 attached to a wall and a plinth A2 attached to the floor are combined with each other. They are fixed to the wall and the floor with finish nails 6, respectively, so as to be independent of each other. The lower plinth A2 is moved together with the floor. The nails for fixing are so designed as to match the shape of a nailer for facilitating the installation. Also, when an adhesive agent is applied to the rear surfaces of the plinths, decorative paper is wound to the rear of the lower plinth so that the adhesive agent becomes ineffective even if adhered to the lower plinth.