the purpose of the present invention is to provide a charged particle beam device and a sample holder for the charged particle beam device by which it is possible to form various environments , and perform in - situ observation and analysis without removing a sample from the charged particle beam device . in the present invention , inserting a detachable reverse side entry portion from a side facing a sample holding means , said portion being provided with a function for changing the state of a sample attached to the sample holding means , makes it possible to observe / analyze changes in the sample by a different process without removing the sample from the charged particle beam device by combining a reverse side entry portion having a different function with the sample holding means . the reverse side entry portion comprises two parts , and a tip thereof , which is one of the parts , is removable . after mounting the reverse side entry portion onto the sample holding means , the sample can be transported while maintaining the same atmosphere , and the sample can be transported between different devices without exposing the sample to air .