This paper proposes the force-based variable compliance control method for a bilateral system which consists of master and slave robots with different degree of freedom (DOF). In order to control the bilateral system with this assumption, bilateral control between master and slave robots for task realization and automation control for adaptation to environment in contact with a slave robot are necessary. In this paper, automation control for adaptation to environment in contact with a slave robot is focused on. Considering the automatic control of slave system, the control method should be switched according to the contact condition. In the case of non-contact motion, the position of the slave system is not decided by using the conventional force controller. Therefore, unexpected contact between the slave system and the object may occur. In order to avoid this unexpected contact motion, the position of slave system should be controlled in the case of non-contact motion. When the slave system contacts the object, the force control should be implemented to achieve the stable contact. In this paper, the force-based variable compliance control method is proposed to achieve 2 desired motion. The validity of the proposed method is confirmed by the experimental results.