An image capturing device includes a taking lens, an image sensor, an image processing unit, an input device, a processor, and a driving unit for moving the taking lens. The image processing unit is configured for receiving the electrical signals from the image sensor and obtaining image information of each image. The input device is configured for selecting focus areas in a photographing area and setting a focus power of each of the focus areas. The processor is configured for performing an auto-focus process using a base evaluation value of an image of the photographing area, wherein the base evaluation value is calculated by taking the total of multiplying an evaluation value of each of the focus areas and non-focus areas of the photographing area by the focus power corresponding to said each of the focus areas and a focus power corresponding to each of the non-focus areas.