Abstract: A collation error indication system for a collator is provided wherein first indication elements for indicating the paper feeding condition of the present collation cycle and second indication elements for indicating the paper feeding condition of at least the immediately before collation cycle are arranged at each paper supply shelf so that the paper feeding conditions of the present collation cycle and the immediately before collation cycle are indicated during each collation cycle. When the abnormal paper feeding occurs, the collation operation is stopped after the collation cycle subsequent to the collation cycle with the abnormal paper feeding has finished. Thus it is easy for the operator to recognize which page should be recollated in the miscollated object, even though a plurality of collation cycles proceed simultaneously.