An information processing apparatus comprising: a storage unit configured to store, for each of a plurality of kinds of display items through one of which an instruction of a user is accepted, a plurality of form images, different in size from each other, for displaying the display items on an operation screen; a reception unit (109, 110, 111) configured to receive first data including instruction information for instructing one of the display items to be displayed, and size information representing a size to display the display items, and to receive second data including the instruction information but not including the size information; a selection unit configured to, in case the first data is received by the reception unit, determine a kind of one of the display items to be displayed based on the instruction information, select a form image, the size of which is suitable for display, corresponding to the determined one of the display items, based on the size information included in the received first data, from said storage unit, and enlarge or reduce the selected form image to make the size thereof coincident with the size represented by the size information, wherein the selection unit is configured to, in case the second data is received by said reception unit, determine a kind of one of the display items to be displayed based on the instruction information, and select a predetermined image of the form images corresponding to the determined one of the display forms from said storage unit; and a display unit configured to display the display item with the selected form image, or with the selected form image enlarged or reduced, on the operation screen. a storage unit configured to store, for each of a plurality of kinds of display items through one of which an instruction of a user is accepted, a plurality of form images, different in size from each other, for displaying the display items on an operation screen; a reception unit (109, 110, 111) configured to receive first data including instruction information for instructing one of the display items to be displayed, and size information representing a size to display the display items, and to receive second data including the instruction information but not including the size information; a selection unit configured to, in case the first data is received by the reception unit, determine a kind of one of the display items to be displayed based on the instruction information, select a form image, the size of which is suitable for display, corresponding to the determined one of the display items, based on the size information included in the received first data, from said storage unit, and enlarge or reduce the selected form image to make the size thereof coincident with the size represented by the size information, determine a kind of one of the display items to be displayed based on the instruction information, select a form image, the size of which is suitable for display, corresponding to the determined one of the display items, based on the size information included in the received first data, from said storage unit, and enlarge or reduce the selected form image to make the size thereof coincident with the size represented by the size information, wherein the selection unit is configured to, in case the second data is received by said reception unit, determine a kind of one of the display items to be displayed based on the instruction information, and select a predetermined image of the form images corresponding to the determined one of the display forms from said storage unit; and determine a kind of one of the display items to be displayed based on the instruction information, and select a predetermined image of the form images corresponding to the determined one of the display forms from said storage unit; and a display unit configured to display the display item with the selected form image, or with the selected form image enlarged or reduced, on the operation screen.