Why my ipad screen is responding by iteself, withuout me touching it?

Nope. It hasn't had any work done to it before.

Try putting the iPad into DFU restore mode and restore the iPad. Be sure to back it up first though as this will erase your content. Google DFU iPad for a step by step instruction.

Otherwise it could be compression damage to the digitizer, something wrong in the logic board or even water damage.

Thanks Cam! I hope your answer works. Although do you know how to DFU restore my ipad?

Connect iPad to your computer and start iTunes. Turn off the iPad. Press and hold Power Button for 2 seconds, then press and hold Home Button. The two buttons are now pressed simultaneously. Wait 12 seconds, then release only the Power Button. Wait another 15 seconds, then release when you see that iTunes has detected your iPad and it is saying the iPad is in "Restore Mode." The screen should be black on the iPad itself. If it shows "connect to iTunes" it means it is in restore mode, which will work as well. As for your iPad doing ghost touch, did you buy it new or used? If used and had been repaired before, it could be a bad part they used. If still new, could need a new screen as well like Cam Smith said. Or could be something else on the logic board. Beware that any repair on this iPad is not an easy one. The iPad Mini is the trickiest of iPads to repair so far, and only the best quality parts should be used (like those sold by iFixit) in case you decide to go down that road.