A sample preparing device has a sample stage that supports a sample and undergoes rotation about a first rotation axis to bring a preselected direction of the sample piece into coincidence with an intersection line between a first plane formed by a surface of the sample piece and a second plane. A manipulator holds sample piece of the sample and undergoes rotation about a second rotation axis independently of the sample stage to rotate the sample piece to a preselected position in the state in which the preselected direction of the sample piece coincides with the intersection line. The manipulator is disposed relative to the sample stage so that an angle between the second rotation axis and the surface of the sample is in the range of 0° to 45°. The second plane corresponds to a plane obtained by rotating around the second rotation axis a line segment which is vertical to the surface of the sample and of which one end corresponds to an intersection between the surface of the sample and the second rotation axis.