Q: When I try to shutdown its automatically restarts and also when I plugin charge then also its starts automatically, only when I force to shutdown like keep on press for 5 second in main button then oly its shutdown fully why?

Hey armohanram,

Please read through the following in full, I think it explains the behavior of your Mac's power button. Ideally, to shut down you would select Shut Down from the Apple menu, or from the shut down dialog pictured below after holding the button for 1.5 seconds:

Using the Power Button to Sleep & Wake

Tap the power button in Mavericks to put your Mac to sleep or to wake it up:

Tap the power button once to put your Mac to sleep. Tap the power button again to wake your Mac.

Press the power button for less than a half a second to sleep or wake your Mac. This duration is similar to pressing the Space bar or Return key to wake your Mac. The power button works this way across all Macs using OS X Mavericks, including both notebook and desktop computers.

Accessing the Shut Down Dialog

Press and hold the power button for 1.5 seconds, to bring up additional options:

Forcing the Mac to Turn Off

Hold down the power button for 5 seconds to force the computer to turn off.  Important: You may lose unsaved documents if you force the computer to turn off this way. Use this method of turning off your Mac only if it has become unresponsive for an extended period of time. Normally you should shut down the computer by selecting Shut Down from the Apple menu, or from the shut down dialog pictured above.

via: OS X Mavericks: Using the power button

http://support.apple.com/kb/HT5869

Sincerely,

Delgadoh