An optical tomographic imaging apparatus configured to take a tomographic image of an object, the optical tomographic imaging apparatus comprising: a light source; means for splitting a light beam from the light source into a measuring beam and a reference beam; a scanning optical system (305, 306) for guiding the measuring beam to the object through scanning; a focusing element; and means (316, 401) for taking the tomographic image of the object by obtaining images split in an imaging depth direction using a return beam corresponding to the measuring beam that is one of reflected beam and scattered beam by the object and the reference beam, and recombining the split images, characterized by a pre-scan setting and imaging device configured to set a focus position of the focusing element roughly and image a tomographic pre-scan image of the object using the means (316, 401) for taking the tomographic image; a focus position setting device configured to set multiple focus positions within a predetermined imaging depth range of the pre-scan image; a reference position setting device configured to set at least two reference positions (701, 702) in an imaging depth direction within the predetermined imaging depth range; a focus detecting device configured to detect a focus condition of in-focus at the at least two reference positions (701, 702), the focus condition meaning correspondence between a position in the pre-scan image and a position of the focusing element; and a focus controlling device (118, 401) configured to perform control of the focusing element so as to perform focusing at the multiple focus positions sequentially based on the focus condition of in-focus detected by the focus detecting device at the at least two reference positions (701, 702), wherein the means (316, 401) for taking the tomographic image of the object are configured to obtain the tomographic image by the focusing performed by the focus controlling device (118, 401). a light source; means for splitting a light beam from the light source into a measuring beam and a reference beam; a scanning optical system (305, 306) for guiding the measuring beam to the object through scanning; a focusing element; and means (316, 401) for taking the tomographic image of the object by obtaining images split in an imaging depth direction using a return beam corresponding to the measuring beam that is one of reflected beam and scattered beam by the object and the reference beam, and recombining the split images, characterized by a pre-scan setting and imaging device configured to set a focus position of the focusing element roughly and image a tomographic pre-scan image of the object using the means (316, 401) for taking the tomographic image; a focus position setting device configured to set multiple focus positions within a predetermined imaging depth range of the pre-scan image; a reference position setting device configured to set at least two reference positions (701, 702) in an imaging depth direction within the predetermined imaging depth range; a focus detecting device configured to detect a focus condition of in-focus at the at least two reference positions (701, 702), the focus condition meaning correspondence between a position in the pre-scan image and a position of the focusing element; and a focus controlling device (118, 401) configured to perform control of the focusing element so as to perform focusing at the multiple focus positions sequentially based on the focus condition of in-focus detected by the focus detecting device at the at least two reference positions (701, 702), wherein the means (316, 401) for taking the tomographic image of the object are configured to obtain the tomographic image by the focusing performed by the focus controlling device (118, 401).