An inspection apparatus is provided, which is operable to inspect a cut sheet that is supplied to a post-processing apparatus that post-processes sheets in units of books and on which an image has been formed by an image forming apparatus. The inspection apparatus inspects an image formed on a sheet for each sheet; manages results of sheet inspection by the inspection unit for respective books including a plurality of sheets; and notifies, the post-processing apparatus of a result of inspecting a book including the sheet that is based on the managed sheet inspection results.