An actuator of a hard disk drive (HDD). The actuator includes an actuator arm installed to be rotatably connected to a base plate of the HDD and having a pivot hole, a VCM (voice coil motor) coil connected to a rear portion of the actuator arm, upper and lower yokes respectively installed upper and lower the VCM coil, a VCM motor having a magnet provided therebetween; and a flexible printed circuit for driving the actuator. Here, a boss is formed at the actuator arm to be face the base plate and to be connected to the flexible printed circuit.