A controlling method suitable for an electronic apparatus is disclosed herein. The electronic apparatus includes a first image-capturing unit and a second image-capturing unit. The controlling method includes steps of: obtaining a plurality of second images by the second image-capturing unit when the first image-capturing unit is operated to capture a plurality of first images for a stereo process; detecting an object in the second images; calculating a relative displacement of the object in the second images; and, determining whether the first images are captured by an inappropriate gesture according to the relative displacement calculated from the second images.