There is a need for inspecting a heightwise variation in a sample. A holder holds a sample. A charge control unit charges the sample held by the holder. A retarding power supply applies a voltage to the sample held by the holder. An electro-optic system radiates an electron beam to the sample applied with a voltage by the retarding power supply and images a mirror electron returning near the surface of the sample. An image processing unit processes a mirror image resulting from imaging the mirror electron. The image processing unit outputs information corresponding to a difference between mirror images, i.e., a mirror image acquired by imaging the mirror electron and a mirror image for a prepared standard preparation, as a heightwise variation in a sample.