An anterior ocular segment optical coherence tomographic imaging device and an anterior ocular segment optical coherence tomographic imaging method that can accurately analyze the shape of a crystalline lens by identifying the boundary of each layer of the crystalline lens in a tomographic image of an anterior ocular segment of a subject's eye, which is taken by optical coherence tomography. A layer boundary detector calculates brightness gradients from brightness values in a tomographic image of an anterior ocular segment of a subject's eye, which is taken by optical coherence tomography, in a depth direction of the tomographic image from a cornea to a retina, detect edges b1, b2, b3, and b4 that are larger than a predetermined threshold, and identify a boundary of each layer of the crystalline lens L from positions of the edge b1, b2, b3, and b4.