A method of manufacturing a resistor integrated with a transistor having metal gate includes providing a substrate having a transistor region and a resistor region defined thereon, a transistor is positioned in the transistor region and a resistor is positioned in the resistor region; forming a dielectric layer exposing tops of the transistor and the resistor on the substrate; performing a first etching process to remove portions of the resistor to form two first trenches respectively at two opposite ends of the resistor; forming a patterned protecting layer in the resistor region; performing a second etching process to remove a dummy gate of the transistor to form a second trench in the transistor region; and forming a metal layer filling the first trenches and the second trench.