An inserter apparatus has a printer A and an inserter apparatus B. The printer A has a print section 13, and an insert information output section 9 for outputting insert information including an insert page showing a position of an insert paper and an interval of printing papers. The inserter apparatus B has a discharged paper carrying section 17 of printing papers from the print section 13; a counter section 19 for counting the number of sheets of the printing papers; a paper feeding section 21 for setting the insert paper therein; and a paper feeding controller 23. Based on insert information from the insert information output section 9, the paper feeding controller 23 controls the insert paper to be fed at a timing before the next paper interval is passed after a count value of the counter section 19 reaches one page before the insert page. Therefore, it is possible to realize an excellent short insert processing for the printing papers.