PURPOSE: To provide the out-of-focus restoring device which restores an out-of- focus image at a high speed with high precision.

CONSTITUTION: The out-of-focus image restoring device consists of a half-mirror 2 and a mirror 3 arranged on the optical axis of a photographic lens 1, a 1st image recording part 5 and a 2nd image recording device 6 which record a 1st and a 2nd obtained image, a 1st Fourier transformation part 7 and a 2nd Fourier transformation part 8 which process those images into Fourier spectra by Fourier transformation, a ratio arithmetic part 9 which finds the ratio from the Fourier spectra, a defocusing quantity determination part 12 which determines a defocusing quantity according to the ratio by using a table 13, and an inverse Fourier transformation part 11 which obtains a restored image from the defocusing quantity, the F number of luminous flux of the photographic lens from an FΔ storage part 10, and the distance Δ between two image formation positions.