1. A multifocus digital image restoration method using an image integration technology, the method, operable in a processor coupled to a memory, comprising causing the processor to: receive a deteriorated image, divide the deteriorated image according to preset Point Spread Functions (PSFs) having different degrees of restoration depending on a focal distance without computing a PSF of the deteriorated image, estimate PSFs in each divided part, generating N restoration images, and sequentially transferring the N restoration images one by one according to the focal distance; determine whether a previously stored restoration image or an integrated image exists, analyze focus deterioration of an input restoration image and the previously stored image when it is determined that the previously stored restoration image exists; compare the analyzed focus deterioration and determining weights of the input restoration image and the previously stored restoration image; integrate the input restoration image and the previously stored restoration image based on the determined weights; compare a degree of restoration of the integrated image with a preset degree of restoration, and output the integrated image as a restoration image when the degree of restoration of the integrated image is higher than the preset degree of restoration.