To provide a puzzle and a block group allowing a player to play and learn mathematics under logical consideration.

This puzzle comprises a plurality of blocks of a polyhedral shape and a box having a cubic internal space in which three perpendicular planes and three planes opposite to them are separately divided, respectively. The same cube as the internal space of the box can be formed by assembling the blocks. Each block group has rectangular solid blocks including a block equal in length on three perpendicular sides, three blocks equal in length on two sides, and six blocks different in length on three sides.