Author : Fumihito Oda Title : The crossed Burnside ring, the Drinfel'd double, and the Dade group of a $p$-group Abstract : Let $p$ be a prime number. This paper solves the question of the difference between the rank of the crossed Burnside ring $B^c(P)$ of a finite $p$-group $P$ and of the rational representation ring $R_{{\mathbb{Q}}} (\mathscr{D}(P))$ of the Drinfel'd double $\mathscr{D}(P)$ of the group algebra ${\mathbb{Q}} P.$ The difference is represented by using the Dade groups of certain subgroups of $P.$ Status : Preprint.