1. An imaging apparatus, comprising: an imaging section; a detecting section to detect an image area of a subject from an image imaged by the imaging section; an area setting section to set one or a plurality of evaluation areas to calculate focusing evaluation values in the image area of the subject in response to detecting an image area by the detecting section; a calculating section to calculate the focusing evaluation values with regard to the one or the plurality of evaluation areas set by the area setting section; and a focusing section to be in focus based on a calculated result by the calculating section, wherein a number of the one or the plurality of evaluation areas set by the area setting section is determined according to a size of the subject detected by the detecting section; and the area setting section sets the one evaluation area when the size of the subject is equal to or less than a predetermined size, and sets the plurality of evaluation areas when the size of the subject is larger than the predetermined size.