Can we make peanut butter with 500W mixer?

While "500 watt mixer" doesn't really tell us any specifics about your setup, considering that right now you've got yourself a nice batch of crushed, or maybe stirred peanuts rather than peanut butter, I'm going to say "no."

To make peanut butter, you either need a grinder in which the grinding surfaces are close enough to make butter, or you need something which has blades that move fast enough while still having enough torque to move through peanut butter.

If the mixer you have is a stand mixer (like a kitchen aid) then there's a good chance you can purchase some sort of attachment which will suit your purposes.

A food processor would do the trick but really low-end models would probably leave a few chunks.

A higher-quality blender would be able to make you a nice smooth peanut butter, but more affordable blenders probably won't have the muscle.

You can also get a hand-crank peanut mill online for less than 50 bucks.

Good luck!

Yes. I have been making peanut butter regularly with my mixer grinder rated at 550W. Grind until it the peanut stops moving, use a spoon/spatula to push the peanut away from the wall of the jar and continue. Repeat the cycle until you get the peanut butter texture. There is no need to add any oil. It will not be as smooth as supermarket peanut butter, but it is more than good enough for me. I make 500grams each time.