Abstract: An information flow out preventing punch for easily punching a hole in an address portion and a magnetic recording portion of a direct mail so that a third person cannot read those portions. The punch is small in size and light in weight and can be put into a drawer of a desk. The punch can punch not only paper but also a plastic card. Resources such as postcards after punched can easily be collected. This information flow out preventing punch includes an operation section and a punch blade group consisting of two or more punch blades. The punch blade group is moved by the operation section so as to punch a plurality of holes in a punch object. In the punch blade group, adjacent punch blades of n-th blade and n+1-th blade are in such a proximity that understanding of the information presented on the punch object becomes difficult.