To easily reverse the difference in the left and right angles of visibility, by making a LCD image plane rotatable 180°, and displaying the former display contents while rotated 180° when the image plane is rotated 180°.

The measured data is stored in a display rear image plane memory 12. An ordinary display mode or a 180° rotation display mode is designated as a display mode on a LCD 16 from a keyboard 20. When the 180° rotation display mode is designated, the LCD 16 is rotated 180°. A graphic display controller 11 copies the contents of the memory 12 onto a image plane memory 13 as it is, in the ordinary display mode. The graphic display controller 11 copies the contents of the memory 12 while rotating the same 180° in a case of the 180° rotation display mode. The contents are read out from the memory 13 by one dot, and the color information is selected from a programmable gate array 14 by a color pallet 15, to be added and displayed on the LCD 16.