1. An image pickup apparatus comprising: an automatic in-focus position determination device which determines an in-focus position of a main subject on the basis of image data; a focus bracket photography device which obtains a plurality of images by successively photographing images while discretely moving a focal position by a predetermined moving amount; a focal position control device which controls the focal position, so as to include the in-focus position of the main subject determined by the automatic in-focus position determination device and focal positions followed and preceded by the in-focus position; a blur amount calculation device which calculates a blur amount according to pixel coordinates; a blurring process device which performs blurring process on the basis of the calculated blur amount; and a recording device which records an image obtained by a predetermined image processing on a recording medium; wherein the blur amount calculation device calculates a blur amount from the plurality of images photographed by the focus bracket photography device, including an image photographed at the in-focus position of the main subject and images photographed at the focal positions followed and preceded by the in-focus position of the main subject; the blurring process device performs blurring process on one frame of a reference image selected from the plurality of images according to a predetermined criteria; and the recording device records the reference image which is blurring-processed by the blurring process device as the image obtained by the predetermined image processing; and wherein the blur amount calculation device calculates the blur amount, so as to make the blur amount larger with the increase of a difference between the focal position of an image having the highest sharpness and the focal position of the reference image.