PURPOSE: To realize a man machine interface which is provided with a mouse input device and which can easily operate a page retrieval system in the mouse input of an information processor having a page retrieval function.

CONSTITUTION: The operation time 5 and the moving distance 4 of a mouse cursor 3 in the mouse input device 1 can be calculated from time and the position of the mouse cursor 3 when the mouse button 1a of the mouse input device 1 is turned on (operation state), and time and the position of the cursor 3 when the mouse button 1a is turned off (non-operation state). The page turning width of page retrieval and page display time are decided by using the calculated operation time 5 and the moving distance 4 as the parameter of the mouse input device 1.