We have achieved injection quantity range enhancement by using the current waveform control technique for direct injection (DI) gasoline injectors. In this study, we developed an injection quantity simulator to find out the mechanism of non-linear characteristics. We clarified the non-linear production mechanism by using the simulator. This simulator is a one-dimensional simulator that incorporates calculation results from both unsteady electromagnetic field analysis and hydraulic flow analysis into the motion equation of this simulation code. We investigated the relation between armature and the injection quantity by using the simulator. As a result, we clarified that the non-linearity was produced by the bounce of the armature in the opening action. Thus, we found that it is effective to reduce the armature bounce to improve the linearity of the injection quantity characteristics.To reduce the bounce of the valve, we devised a current waveform control technique that includes a current cut-off part just after the armature launching. This current waveform decelerates the armature just before the armature collides into the magnetic core. As a result, the armature bounce can be reduced.This paper discloses the details of this current waveform and the armature motion by using the developed simulator. Furthermore we discuss whether the developed waveform can improve the injection quantity linearity by using both the simulator and experimental results. Finally, we conclude that the waveform can achieve the minimum injection quantity reduction.