A cross-section processing and observation method includes: forming a first cross section in a sample by etching processing using a focused ion beam; obtaining image information of the first cross section by irradiating the focused ion beam to the first cross section; forming a second cross section by performing etching processing on the first cross section; obtaining image information of the second cross section by irradiating the focused ion beam to an irradiation region including the second cross section; displaying image information of a part of a display region of the irradiation region from the image information of the second cross section; displaying the image information of the first cross section by superimposing it on the image information being displayed; and moving the display region within the irradiation region. Observation images in which display regions are aligned can be obtained while reducing damage to the sample.