Method for Adjusting Height of Sample and Observation System

In a device for performing observation with a charged particle microscope at an atmospheric pressure using a diaphragm, while there was a demand that a distance between the diaphragm and a sample be reduced as much as possible, there was a problem that a limit for how close the diaphragm and the sample can be brought to each other was unknown in the past. In the present invention, a height adjustment member is used, and the position of a diaphragm in a charged particle beam device with respect to the height adjustment member is defined as the specific point of an optical device, so that the positional relationship between the height adjustment member and the diaphragm in the optical device is reproduced, and the height of a sample table with a Z-axis driving mechanism is adjusted so as to locate the surface of the sample at the position of the specific point of the optical device. According to this, the distance between the diaphragm and the sample can be safely and simply adjusted, and thus, an object is to adjust the distance between the diaphragm and the sample so that the distance is reduced as much as possible or the distance is fixed every time the sample is replaced.