A portable information device includes: a chassis; a decorative plate fixed to a part of an outer face of the chassis with stretch releasable double-sided adhesive tape; and a cover member that covers the outer face and the decorative plate. The double-sided adhesive tape has: an adhesive portion including adhesive layers on first and second faces of a substrate for adhesively fixing between the decorative plate and the outer face; and a tab including release paper partially covering the adhesive layers to let a user hold the tab for stretch release of the adhesive portion from between the decorative plate and the outer face. The double-sided adhesive tape has a first groove and a second groove on the first face and the second face, respectively, that are positioned not to overlap in a thickness direction of the substrate.