PURPOSE: To efficiently carry out grinding work by conveying a sample to a table for grinding with a first tip and then, by grinding it with a second tip which can carry out finer grinding than the first tip.

CONSTITUTION: A sample is mounted on a table and conveyed in the desired direction. A driving means rotates and drives a blade 30 in which a first tip 32a is provided opposed to the table separated by a predetermined distance so that the sample is brought into contact. Also, a second tip 32b which can carry out finer grinding than that by the first tip 32a is provided at the blade 30 ahead of the first tip 32a in the conveying direction and separated from the table by a predetermined distance. The sample is ground by the first tip 32a and then, further ground by the second tip 32b.