An image forming apparatus that enables a user to check results of test printing quickly. An MFP as the image forming apparatus is connected to an external finisher as a post-processing apparatus that performs post processing on printed recording media. The MFP and the external finisher are controlled independently of each other. The MFP is comprised of a printer controller configured to execute test printing of a printing object, and a conveyance controller configured to perform control such that when executing the test printing, printed recording media are not conveyed to the external finisher.