Abstract: A method of measuring a retinal layer includes obtaining an OCT layer image of a retina, detecting a reference boundary line indicating a retinal layer in the obtained OCT image, obtaining an aligned OCT image by aligning a vertical position of each column of the OCT image so that the detected reference boundary line becomes a baseline, predicting retinal layer regions from the aligned OCT image, calculating boundary lines between the predicted retinal layer regions, and restoring the calculated boundary lines to positions of the boundary lines of the retinal layer of the original OCT image by aligning the vertical positions of the calculated boundary lines of the retinal layer for each column so that the baseline becomes the reference boundary line again.