An apparatus for heating a sample within a vacuum chamber according to the present invention includes a preliminary exhaust chamber connected with a vacuum chamber of an analyzer and the like through a gate valve. A sample stage is disposed within the vacuum chamber, and a sample holder is detachably disposed on this stage. The preliminary exhaust chamber is provided with a transfer device for transferring the sample holder between the preliminary exhaust chamber and the vacuum chamber to mount the sample holder on the stage and detach the sample holder from the stage. The sample holder is provided with a heater and a temperature-measuring element mounted thereon, the heater and temperature-measuring element being connected with the respective connectors mounted on the sample holder. A fixed connector is connected with the connectors when the sample holder is mounted on the stage by means of the transfer device.