<p>SMA (Shape Memory Alloy) wire actuators can shorten their length by applying electricity. They have big power per their volume and often used for robots that need smaller body and bigger force. SMA wire has an initial electrical resistance and changes it while shrinking. We can control SMA shrinkage indirectly without other sensors by managing the electrical resistance. We made SMA tube unit that can bend in multi-direction with three SMA wires. The unit can move silently and quickly. It can be used for small snake robot or multi-direction flexural arm robot by being combined.</p>