Laptop automatically powers on when plugged in for charging

I am having this problem for past a week.as soon as the charger is plugged into the laptop, the laptop gets automatically turn on (without pressing the power button). The laptop fully boot and not geving any other problem.
A laptop should turn on only when the power button is pressed. What makes the power bypass the power button and turn on? i don't know why this stupid laptop behaving like this i am very frustrated now because when i plugged it in it gets boot and i have to manually shuts it down every time.
please help me.

Maybe a BIOS setting? In my BIOS I can set my computer to automatically restart when power is restored, of course mine is a desktop so it doesn't have a battery, but probably worth checking.

I agree - I also suspect this is a setting in your BIOS. While PC power settings are different than notebooks (since PCs don't run on batteries), there may be a setting your BIOS that says to boot when the charger is connected. I would check your owners manual.

thank you both of you for replaying.
i have check BIOS but i coudent find that option so can you please tell me
that where exactly i find that option?

Don't know, I don't have the same computer. Take some photos of your BIOS screens and then post them here.

And we don't know what notebook you have anyway.

Based on his system specs I did my searches on a Dell Inspiron 1510

My son, who is a dell field repair man, was visiting as this thread was posting.. He states that there are two problems. It is the CPU, which he says is unlikely,. or a motherboard fault. In either case, it would need a motherboard replacement.

Suggestions. If you are able, get to the motherboard and see if it could be cleaned up a little, there could be a deposit causing a short on the power switch.. Under these circumstances, in his daily work, he would change the motherboard. If you are not under guarantee, the cost of this would be prohibitive.

Thank you all for helping me. i just want to know that what if i dint repair it i mean its not a big problem for me ya its a lil bit anoying but i can menage that i dont want to change my motherbord.

BUT i also dont want to take any risk. Can it become a majore problem in future?
Will it demage my laptop?
plz help me.

Leaving a notebook plugged in 24/7 has been known to shorten the life of the battery. But generally, the notebook itself should be fine.