183 of the button 180 that is exposed out of the casing 101 of the portable electronic device is pressed the pressing projection 184 fig2 moves down thereby pressing the second tact switch 170 the second tact switch 170 being pressed transmits a predetermined signal to the controller not shown the rotation knob 140 can smoothly rotate due to its first and second shafts 143 145 that are respectively supported by the vertical rotation switch 130 and the holder 160 also since the rotation knob 140 is supported at both sides the size of the knob body 141 of the rotation knob 140 can be selected according to the user 39 s convenience and the size of the device when the user presses the rotation knob 140 the second shaft 145 that is disposed above the first tact switch 150 moves down thereby pressing the first tact switch 150 accordingly the controller perceives that the enter function has been performed operation of the scroll key 100 having a function selecting switch as described above and as mounted in a camcorder and used for manual focusing and a menu selection key will be described hereinbelow when the user wants to manually focus the camcorder lens the user presses the touch surface 183 of the button 180 that is exposed out of the camcorder casing 101 as shown in fig6 then the controller perceives the vertical rotation switch 130 to be the manual focusing key that focuses the camcorder lens therefore by rotating the rotation knob 140 that is engaged with the rotation switch 130 the user can focus the camcorder lens if the user wants to select a specific menu in the menu screen displayed on the display panel the user re presses the touch surface.