An electric control device includes: a cam having a variable distance between an outer periphery and a center; a control shaft having one end, which contacts the outer periphery of the cam, and displaceable according to a rotation of the cam to adjust a valve lift amount; a motor rotating the cam; an angle detector detecting a rotation angle of the cam; and a controller. The cam includes multiple steps arranged on the outer periphery. The controller controls the rotation of the cam through the motor to match a detection angle of the angle detector with a target angle corresponding to a target valve lift amount. The controller stops rotating the cam through the motor when a difference between the detection angle and the target angle exceeds a first threshold, and the target angle corresponds to one of the steps.