1. An imaging apparatus comprising: an imaging section configured to acquire a plurality of images that are consecutively taken in time series by an imaging device; a reference region setting section configured to employ one of the images acquired by the imaging section as a reference image and to set a region of the reference image as reference region, the region having high-frequency components; and an image processing section con figured to combine the images including the reference image by positioning the images so as to overlap subject portions in each images, the subject portions being defined in the reference region set by the reference region setting section.