A reference point-designating section 18b designates two reference points on a measurement object. A reference curve-calculating section 18c calculates a reference curve calculated by approximating an outline of the measurement object based on the reference points. A loss-composing point-calculating section 18d calculates loss-composing points constituting a loss outline formed on the measurement object based on the reference points and the reference curve. A loss size-calculating section 18f measures loss size based on the loss-composing points. Designating two reference points enables loss size measurement, thereby reducing complex operation and improving operability.
