Disclosed herein is a device for selectively limiting both rotational directions of a steering wheel, and provided is a steering angle limiting device of a steer-by-wire (SBW) system including a stopping gear configured to be rotated together with a steering shaft; a cam configured to receive a rotational force of an actuator and to be eccentrically rotated; and a stopper configured to be rotated in response to rotational operation of the cam and selectively engaged with gear teeth of the stopping gear, thereby restricting selectively forward and reverse directional rotations of the stopping gear.