High-resolution electron cryo-microscopy is one of good candidate for structure analysis of membrane-protein, and also actually analyzed the structure of membrane-proteins such as bacteriorhodopsin (bR) and plant light-harvesting complex (LHC). By developing an expeditious method for structure analysis up to atomic or near atomic resolution, we would like to interpret a function of protein from the structural point of view. However, there are some difficulties in electron microscopy for structure analysis of protein. Especially, the most serious problems are the specimen damage caused by electron irradiation, the denaturation of biomolecules caused by dehydration and missing high-resolution data on electron micrographs at high-tilted angle.The irradiation damage at 8K has been found to be reduced to 1/20 compared with that at room temperature. We have, therefore, developed a high-resolution electron cryo-microscope and improved it by which images can be recorded with higher resolution than 3 Å at a specimen-stage temperature of 4.2 K, even when the specimen is highly tilted. The highly tilted data are essential for reduction of the missing corn effect.