A corneal endothelial cell photographing apparatus for photographing endothelial cells of a patient eye's cornea, includes: a cornea photographing optical system including an imaging device and configured to project light toward the cornea and photograph the corneal endothelial cells through the imaging device; a light projecting optical system to project detection light in a first oblique direction to the cornea to detect a focus state of the cornea photographing optical system relative to the cornea; a detecting optical system including a detector with arranged pixels and configured to receive, in a second oblique direction opposite to the first oblique direction, corneal reflection light resulting from the detection light and including reflection light from the corneal endothelium through the detector, and detect an intensity distribution of the corneal reflection light in a depth direction; and a controller to cause a monitor to display the intensity distribution output from the detector.