Provided are an electronic control suspension apparatus and a damping force controlling method thereof, which are capable of changing a damping force of a damper by just manipulating a multistep switch even during driving. The electronic control suspension apparatus for controlling a damping force of a damper installed at each of a front wheel and a rear wheel includes: a multistep switch disposed in a vehicle and configured to change the damping force of the damper in a multistep manner between a hard step and a soft step; and an electronic control unit configured to control the damping force of the damper according to a current amount corresponding to a step selected from the multistep switch, the current amount to be applied to a solenoid valve being preset for each step of the multistep switch.