\input amstex \magnification=1200 \hsize=138 true mm \vsize=217 true mm \def \nl{\hfill\break} \def \nph{\hfill\break\indent} \def \newpage{\vfill\break} \def \p{^{\wedge}_p} \documentstyle{amsppt} \leftheadtext{ } \rightheadtext{ } \document Toral groups and classifying spaces of $p$--compact groups Kenshi Ishiguro Fukuoka University, Fukuoka 814-0180, Japan We show converses to some known results for the classifying spaces of $p$--toral groups or $p$--compact toral group. Suppose $G$ is a compact Lie group. The following results are included. (A) If there is a positive integer $k$ such that the $n$--th homotopy groups of $(BG)\p$ are zero for all $n \ge k$, then $(BG)\p$ is the classifying space of a $p$--compact toral group. (B) If the canonical map $Rep(G, K) >>> [BG, BK]$ is bijective for any compact connected Lie group $K$, then $G$ is a $p$--toral group. We will also discuss the conditions of a compact Lie group that its loop space of the $p$--completed classifying space be a $p$--compact group. \end