In a shift amount calibration mode, a calibration unit (62d), while increasing by stages a shift amount of the incidence end of an image guide (31) from a base point where the shift amount is 0 to a position where the shift amount is a regulated amount, reciprocates the incidence end of the image guide (31) between the base point and positions separated by respective shift amounts, causing a CCD (58) to capture an image of a calibration chart (94) having a regular pattern of black and white stripes at the base point and positions separated by the respective shift amounts. The calibration unit (62d) detects the black density of the captured image, matches a shift direction and the direction of the pattern of the calibration chart (94) on the basis of the black density, and determines, on the basis of the result of comparing the previously stored variation profile of the black density with the detected density, the driving condition of a piezoelectric element (35) so that the shift amount of the incidence end of the image guide (31) becomes the regulated amount.
