2010 Mazda 3 sport, GX 2.0L

[Franklinprc]

I felt vibration while I press the break, is it the break problem?
if it's the break problem, which portion I need to change? break pads the rotors?

[tmpz]

I felt vibration while I press the break, is it the break problem?
if it's the break problem, which portion I need to change? break pads the rotors?

Probably warped rotors. Get it checked by a mechanic.

If it's warped rotors, well obviously change rotors, but you might want to change the brake pads as well if they are worn out.
Don't cheap out and get generic rotors, get Mazda rotors from one of the affiliated dealerships with TM3 member discounts.