In a method for operating a semiconductor device, the method may include: sorting program states of a memory cell that stores multi-bit data into a plurality of groups; applying different bias voltages to bit lines corresponding to a selected group among the plurality of groups; applying a program voltage to a selected word line corresponding to the selected group; verifying whether each of selected memory cells corresponding to the selected word line is programmed to a respective target program state; applying an inhibition voltage to bit lines coupled to programmed memory cells; and selecting a next group to be programmed until the plurality of groups are programmed.