PURPOSE: To satisfactorily block sheets which are staggered and conveyed, by inserting a blocking plate into a sheet direction turning section on a first conveyer, and by moving the same while a second conveyer is run at a high speed so as to convey downstream sheets.

CONSTITUTION: A blocking plate 28 is inserted between sheets 1 which are staggered and conveyed on a first conveyer 3, in a section where the direction of the sheets 1 is turned, and then the blocking plate 28 is moved in the flowing direction of the sheets 1 while a second conveyer is run at a high speed. As a result, the sheets posterior to the blocking plate 28 are blocked, and thereafter, the sheets downstream of the blocking plate 28 are rapidly conveyed by the high speed second conveyer 4, thereby it is possible to satisfactorily block the sheets which are staggered and conveyed. Further, the blocking plate 28 is moved so that it is possible to prevent the blocked sheets from being bulged up while there is no trouble upstream of the blocking plate.