PROBLEM TO BE SOLVED: To display respective images with high image quality even when an electronic shutter function is made to act under the situation of displaying a plurality of special observation images using a rotary filter.SOLUTION: In a special observation mode, the rotary filter is arranged on an optical path, and white light for normal observation and special light of a specific wavelength region are alternately radiated in each field period. Then, when the electronic shutter function is turned to an ON state, the phase of the rotary filter is delayed by a period &DgrT, and the rotary filter is rotated at an equal speed in the state of shifting the phase.
