A method for controlling an optical power level includes the steps of a) regularly increasing a control value of a driving signal generator for driving a pickup unit adapted to output an optical power, b) checking a driving signal of the driving signal generator according to the increasing control value, and c) setting a control value at which the driving signal begin to be generated as an offset value for setting up an optical power. Therefore, an offset value for a reference optical power needed for setting up laser power levels for individual operation modes is more accurately calculated, and the laser power levels for individual operation modes are optimally controlled based on the offset value.