A camera module actuator includes: a magnet disposed on a lens barrel; a driving coil disposed opposite to the magnet; and a driving device including a comparer that calculates an error value by comparing a target position of the lens barrel with a current position of the lens barrel, a controller IC that generates a control signal by applying control gains to the error value, and a driving circuit that generates a driving signal in response to the control signal. The controller IC determines the control gains based on a friction coefficient between a guide groove guiding movement of the lens barrel and a ball bearing contacting the guide groove. The controller IC provides a detection signal having a gradually increasing level to the driving coil, and determines the friction coefficient based on a level of the detection signal at a point in time of movement of the lens barrel.