Micro-manipulation is quite required because this makes it easier to do delicate work. This technique can be applied in various departments. However, it is difficult for operator to manipulate by their hands because objects are too small and fragile. Moreover, operators can obtain only visual information at present, and cannot recognize how much force applied to objects. In order to solve these problems, haptic information is essential. Scaling bilateral control is an effective method to amplify force feedback. However, friction makes control system unstable even if force scaling gain is too high. Force scaling gain should be high only when slave robot contacts environment. This paper proposes a method of variable scaling bilateral control based on environmental impedance estimation. Proposed method enables to judge the state of contact with environment and to raise force scaling gain automatically during contact motion. Finally, the effect of proposed method is verified through the simulation and experiment.