A method of determining a position of a focus lens includes the steps of detecting luminance values corresponding to a plurality of imaging elements which detect light via a focus lens while moving the focus lens, calculating a contrast value for evaluation of a focused state of a subject image on the basis of the detected luminance values corresponding to the imaging elements, specifying the largest luminance value in the detected luminance values corresponding to the imaging elements, specifying a range in which the largest luminance value is not less than a value which is determined in advance in a moving range of the focus lens and determining the position of the focus lens on the basis of the contrast value in the specified range of the position of the focus lens.