An optical coupling element of the invention includes: a plurality of incident surfaces having a predetermined curvature, where light emitted from a plurality of light-emitting elements is respectively incident; a reflective surface reflecting the light incident respectively on the incident surfaces and having a predetermined curvature; and a plurality of output surfaces respectively outputting the light reflected by the reflective surface toward an end face of an optical fiber and having a predetermined curvature. The curvatures for the incident surfaces, the reflective surface, and the output surfaces are adjusted such that the X-direction tolerance is greater than the Y-direction tolerance. Here, the alignment direction of the plurality of incident surfaces is the X direction, the advancement direction of the light is the Z direction, and the direction perpendicular to the X and Z directions is the Y direction.