A specimen box for an electron microscope capable of observing a general specimen or a live cell is formed of a housing. The housing includes a receiving chamber formed therein and at least one view hole formed on each of a top side thereof and a bottom side thereof and communicating with the receiving chamber and coaxially aligned with the other. The distance between a bottom end of the view hole located on the top side of the housing and a top end of the view hole located on the bottom side of the housing is smaller than 50 μm. The housing is ultra-thin to enable penetration of the electron beam therethrough even though a liquid specimen is injected into the housing. A general specimen or a live cell can be put into the housing for the microscopic observation under the electron microscope.