This invention is to provide a shape measuring device and a shape measuring method that can accurately measure a cross-sectional shape or a three-dimensional shape of a sample without using matching of characteristics. A shape measuring apparatus comprises a charged particle beam apparatus comprising a processor for measuring detected charged particles signal generated from the sample. The charged particle beam is irradiated to sample at first angle to generate a first signal and second angle to generate second signal. The processor selects a parameter indicating a relation between the first signal and a height of the sample or an inclination angle of the specimen until the first signal which achieves the second signal.