Data input processing is initiated when an ADD-IN button is pressed in a condition where a data cell of a spreadsheet application is selected. Whether an editor is already activated is determined and, if such is the case, a current mode of the currently activated editor is detected and, if it is activated in an edit mode and an activation mode set in activation setting processing is the edit mode, acquired data is added to the currently activated editor and put in a selected state and displayed on an edit screen.