1. An image input/output apparatus comprising: an input unit configured to input a plurality of sets of document data; a determining unit configured to determine whether an input process for the plurality of sets of document data is ended; an output unit configured to output the plurality of sets of document data input by said input unit, as a single group of data, if said determining unit determines that the input process for the plurality of sets of document data is ended; a setting unit configured to set a condition for outputting the plurality of sets of document data, including a first set of document data and a second set of document data, in a sheet insertion mode where the condition is set during a period between when said input unit finishes inputting the first set of document data and when said input unit begins inputting the second set of document data, and before said output unit outputs the plurality of sets of document data including the first set of document data and the second set of document data, wherein in the sheet insertion mode, on each print sheet at least one of the plurality of sets of document data inputted by said input unit is printed and a particular sheet is inserted between print sheets, and wherein said output unit outputs the plurality of sets of document data including the first set of document data and the second set of document data in the sheet insertion mode based on the condition set by said setting unit.