PURPOSE: To make it possible to move a sample, to operate and adjust a high voltage system, a lens system, and a deflection system by switching a clutch by providing a sample movement knob with the clutch and a detector such as a rotary encoder.

CONSTITUTION: A sample movement knobs 2, 3, and a set of an X-axis clutch 14, a Y-axis clutch 15, an X-axis rotary encoder 16, a Y-axis rotary encoder 17 are provided at the front ends of an X-axis sample movement drive rod 12 and a Y-axis sample movement drive rod 13. Positioning a selection switch 18 to the sample movement, engaging the clutches 14 and 15, and driving the sample movement drive rods 12, 13 with the sample movement knobs 2, 3, the sample is moved to a proper position. For controlling a high voltage system, the selection switch 18 is set to a specified position and a signal switching circuit 19 is accordingly switched. The clutches 14, 15 are disengaged, the sample movement knobs 2, 3 rotates the rotary encoder 16 or 17, and via the signal switching circuit 19, an up-down counter 20 high voltage circuit 21 is actuated, and a voltage corresponded with a count value is outputted. A similar operation is performed for the lens system or for the deflection system.