The present invention makes it possible, even when using an ordinary electron beam device (not an environment-controlled electron beam device), to create locally a low vacuum condition in the vicinity of a sample and cool said sample by means of a sample holder alone, without modifying the device or adding equipment such as a gas cylinder. The sample to be observed is placed in a sample holder provided with: a vessel that can contain a substance to serve as a gas source; and a through-hole in the bottom of a sample mount on said vessel. Via the through-hole, gas evaporating or volatilizing from the vessel is supplied to the sample under observation, thereby creating a localized low-vacuum state at or in the vicinity of the sample. Also, the heat of vaporization required for volatilization can be used to cool the sample.