PURPOSE: To position a sample automatically, by calculating deviation between a specified measuring image position and a sample image presently an electrically operated XY table based on feature quantity of a binary pattern to move the electrically operated XY table so that a sample will come to a specified measuring image position.

CONSTITUTION: This apparatus is provided with a TV camera 1 for converting a sample into an image, a circuit 2 for binary coding an image, an arithmetic control section 3 adapted to calculate the feature quantity of a binary pattern to control the apparatus and an electrically operated XY table 4 for positioning samples. To position a sample, first, deviation is calculated between a specified measuring image position and sample image presently on the table 4 based on the feature quantity of a binary pattern of the sample to move the table 4 automatically so that the sample will come to the specified measuring image position. thus, when samples of the same shape previously arranged on the table 4 are measured, any deviation can be corrected automatically regardless of errors in the interval of the samples thereby assuring accurate measurement.