Lateral loss of balance is frequent fall reasons among older adults and especially Parkinson’s patients. In the case of a lateral loss of balance, smart walkers have not any safety measure for tipping. In this reason, we propose an automatically initiated lateral support mechanism against sudden unexpected lateral instability. Proposed mechanism is driven a linear actuator and is triggered two ways. One is that exceeding critical threshold value determined for force/torque sensor. Other is that much longer than required swing phase during gait. In this paper, we introduced mechanical properties of proposed mechanism such as: kinematics of mechanism, kinetic of mechanism, anti-tipping effectiveness of mechanism, structural analysis of walker, structural analysis of lateral support mechanism. Additionally, we put forward control algorithm and trigger structure of proposed lateral support mechanism. At the near future, depending on improving safety measures and decreasing tipping risks, smart walkers may be one of the first option between mobility assistive devices for elderly population.