In an image input apparatus which can be controlled by a host computer, and has a request sending unit for sending a request input by the user to the host computer, an internal command execution unit for executing the request, and a request route flag table which stores correspondence data of the request type and destination, the user input is accepted, a request in a predetermined format is generated on the basis of the accepted user input, and the generated request is sent to the request sending unit or command execution unit with reference to the request route flag table.