This paper reports key issues of packaging for sensor and actuator MEMS (Micro Electro Mechanical Systems) devices. In this paper, we focus on the two types of MEMS devices, the sensor MEMS and the actuator MEMS. In the case of sensor MEMS packaging, the thermal stress is the most important in order to prevent the deterioration of its sensitivity. On the other hand, in the case of actuator MEMS packaging, it is important to design the packaging for enhancing the device characteristics.