Most of the mechanical logic metamaterials/structures are bistable/multi-stable, and few existing works have been found to realize mechanical logic from the mechanism perspective. Here, we design a conductive module metamaterial inspired by a planar 4R mechanism to achieve mechanical logic based on its reconfigurability. By utilizing the motion bifurcation to realize the transformation between configurations, we realize logic gates and corresponding combinations (including half/full adder/subtractor). Since elastic deformation occurs only on hinges, the module can automatically return to its initial state after one computation for reuse. This work provides a new idea for the design of mechanical logic/computation.