A method for measuring a three-dimensional shape of an object surface using a digital hologram for recording an interference fringe pattern projected onto the object surface, comprising the steps of: a projection step for projecting the interference fringe pattern having a single spatial frequency (fi) generated by interference between laser beams (L1, L2) from a laser of a monochromatic coherent light source onto the object surface; a recording step for recording the interference fringe pattern projected onto the object surface by the projection step as the digital hologram using reference light from the laser and a photo detector; and a measurement step for generating a plurality of reconstructed images having different focal distances by computation from the digital hologram recorded by the recording step, and deriving the distance to each measurement point on the object surface by computation by carrying out a focusing method which determines one of the plurality of reconstructed images in which the interference fringe pattern is in-focus at the measurement point and the focal distance of the determined reconstructed image is taken as the distance to the measurement point, wherein the measurement step comprises an interference fringe pattern extraction step for respectively extracting the component of the single spatial frequency (fi) corresponding to the projected interference fringe pattern from each of the plurality of reconstructed images by spatial frequency filtering, and respectively obtaining interference fringe images made from the extracted components, wherein the obtained images are of reduced influence of speckles and the focusing method is applied to the obtained images. a projection step for projecting the interference fringe pattern having a single spatial frequency (fi) generated by interference between laser beams (L1, L2) from a laser of a monochromatic coherent light source onto the object surface; a recording step for recording the interference fringe pattern projected onto the object surface by the projection step as the digital hologram using reference light from the laser and a photo detector; and a measurement step for generating a plurality of reconstructed images having different focal distances by computation from the digital hologram recorded by the recording step, and deriving the distance to each measurement point on the object surface by computation by carrying out a focusing method which determines one of the plurality of reconstructed images in which the interference fringe pattern is in-focus at the measurement point and the focal distance of the determined reconstructed image is taken as the distance to the measurement point, wherein the measurement step comprises an interference fringe pattern extraction step for respectively extracting the component of the single spatial frequency (fi) corresponding to the projected interference fringe pattern from each of the plurality of reconstructed images by spatial frequency filtering, and respectively obtaining interference fringe images made from the extracted components, wherein the obtained images are of reduced influence of speckles and the focusing method is applied to the obtained images.