A sample transfer device is provided which can insert to a charged particle beam apparatus a sample to be observed and analyzed under irradiation of a charged particle beam while suppressing to a minimum the time to expose the sample to the atmospheric environment. The sample transfer device for transferring the sample to be observed and analyzed by irradiating the charged particle beam comprises an expansible hollow member capable of accommodating a sample holder mounting the sample, a fixing member for fixing the sample holder within the expansible hollow member, and a sealing member communicating with the interior of the expansible hollow member to open/close an opening through which the sample holder passes.