1. An auto-focus apparatus utilized for an image pickup apparatus having a focus ring comprising: an evaluation value calculator periodically calculating a plurality of evaluation values for a plurality of areas of a subject image based on high frequency components of image signals of the plurality of areas of the subject image; and a control unit, after detecting that manual operation of the focus ring has been stopped, (a) automatically selecting one of the plurality of areas as a selected area containing a manual user desired  in-focus state based on a ratio of the evaluation value detected when the manual operation of the focus ring has stopped and the evaluation value at a start of the manual operation, (b) performing auto-focus image processing on the selected area of the plurality of areas of the subject image, and (c) outputting instruction signals for moving a focus lens based on a peak of the evaluation values obtained by the image processing.