Illumination light is lighted, and specific light is repeatedly lighted and dimmed at a specific frame interval. Based on a first captured image obtained by imaging the subject illuminated with the illumination light and a second captured image obtained by imaging the subject illuminated with the illumination light and the specific light, a position of a specific region (spot SP) to be obtained based on the specific light (auxiliary measurement light) in the second captured image is specified. The first captured image or the second captured image is processed to generate a specific image, based on the position of the specific region. The specific image is displayed on a display unit.
