And if you touch metal,like strings, the hum/buzz desapear ?

If yes, it is a ground missing in your guitar.

If no , try another amp.

Something you might wanna consider.....60-cycle hum is common with single coils. The CP '50's Strat has a reverse wound middle pickup, making the 2 and 4 positions on your pickup selector hum-cancelling. Before taking the guitar anywhere or doing anything with it, you might want to check that you still have the buzz at all five of a pickup postions. It could just be the usual hum from single coils maybe being enhanced by something electrical nearby.

It is not the case her as AndyVogel touch a metal and the hum/buzz desapear ; I is not a single coil problem.

In my experience, what you've got isn't a grounding problem, but a screening problem. Fender use un-screened hook-up wire inside their guitars: very vintage, but electronically not good practice. And to make things worse, they only screen the internal body cavities on some models, definitely not all. The back of your guitar's pick guard may be screened, but that's not really enough.

When you have the guitar in front of you (but don't touch the metal bits) your body's acting like a big aerial, picking up radio interference, mains hum and all sort of stuff and this is picked up by the unscreened wiring in your guitar. When you touch the strings or bridge your body is earthed and the hum stops.

The only real cure for this problem is to screen the body cavity, either with conductive paint or copper foil. Just make sure that the screening is ultimately connected to an earth point in the guitar (usually one of the pot bodies). Plenty of websites out there will give you loads of information on the various ways to screen the body.

My USA Deluxe Tele has a screened body and Vintage Noiseless pickups and is quiet as a church mouse. I fitted my MIM Strat with VNs but it was still noisy until I screened the body. Surprisingly my CS Custom Deluxe Strat wasn't screened either (it is now!). My most recent Fender acquisition - a Jaguar Blacktop HH - still needs doing, as it's noisy even though it has twin humbuckers.

Hope that helps, anyway.

Shielding the body cavities is a huge waste. Adding foil can alter the tone of the guitar much like changing the tone cap value or type, and it doesn't do much for electrical interference. Shielding completely misses the pups, which is where the noise comes from anyway, so it doesn't block the interference at all. It is the pickups that "pickup" the noise, not the body cavities. You can get the same results as shielding by adding another cap across the output, muffling the noise but not blocking it, which changes the tone from the guitar.