1. A method for obtaining a transmission electron microscope image, the method comprising: attaching a mesh, which holds a specimen, to a specimen stage; emitting a charged particle beam from an electron gun; detecting said charged particle beam passing through the specimen by an imaging device; obtaining a transmission electron microscope image by the imaging device; in the case where a number of pixels having a gray value indicating a grid of said mesh is not less than a predetermined percentage of a number of pixels of a monitoring region, removing pixel data having said predetermined gray value, converting the gradation scale to an other gradation scale and obtaining a transmission electron microscope image; and displaying the transmission electron microscope image in a monitor.