With the rapid development of modern technologies

academic circles have paid more andmore attention to the research of micro machines.The micromachines are various

for exam-ple

self-controled micromachines can safeguard and inspect in some narrow and dangerousplaces;some of them can enter man's cavities even blood vessels to examine and operate thediseased parts;the microactuators in the scanning tunneling microscope(STM)and atomicforce microscope can reach a resolution in nm. Recently

in order to improve the research inmicromachines

microactuator and microrobot

contests which are composed of climbingmoutain. climbing cliff

selfshow etc.are held periodically in Japan. Because micromachinemust be movable

the microactuators become the most important in the domain of micromachines. This paper summarizes the principles of micromachines and microactuators

and thecontests at abroad.