A method and an apparatus for acquiring an image of a subject are provided. The method for acquiring the image of the subject includes acquiring a first preliminary image and a second preliminary image of the subject through an image sensor operatively coupled to an electronic device, determining a candidate emission time relating to an acquisition of an output image of the subject, based on a difference between state information of at least part of the first preliminary image and state information of at least part of the second preliminary image, comparing the candidate emission time with a time corresponding to a synchronization period where a plurality of lines of the image sensor simultaneously acquires the output image, and acquiring the output image of the subject based on the comparison.