To improve an apparatus reliability by applying a voltage suitable to a situation, a charged-particle-beam apparatus 1 of the present invention includes: a sample stage 25; an electrostatic chuck 30; and an electrostatic-chuck controlling unit 13, and generates an image of a sample 24 by irradiating the sample 24 held on the sample stage 25 by the electrostatic chuck 30 with an electron beam 16. The electrostatic-chuck controlling unit 13, when the electrostatic chuck 30 holds the sample 24, applies a preset initial voltage to a chuck electrode of the electrostatic chuck 30; determines whether or not the sample 24 is normally clamped to the electrostatic chuck 30; and increases the voltage applied to the chuck electrode until determining that the sample 24 is clamped normally to the electrostatic chuck 30 if determining that the sample 24 is not clamped normally to the electrostatic chuck 30.