An optical coupling element which is configured to be disposed between an optical fiber and an optical element that face each other in order to optically couple the optical fiber and the optical element, the optical coupling element comprising: a substantially cylindrical optical coupling portion whose opposite end surfaces (10a, 10b) respectively face the optical fiber and the optical element; and a projection projecting from a periphery (10c, 10d) of the optical coupling portion in a radial direction, the projection being located closer towards one of the opposite end surfaces (10a, 10b) with respect to a center position between the opposite end surfaces (10a, 10b), wherein a diameter of the optical coupling portion at a position corresponding to a first end surface of the projection is substantially equal to a diameter of the optical coupling portion at a position corresponding to a second end surface of the projection, and wherein the periphery (10c, 10d) of the optical coupling portion includes periphery surfaces (10c, 10d) that are tapered from the positions corresponding to the first and second end surfaces of the projection re-spectively towards the opposite end surfaces of the optical coupling portion and wherein the optical coupling portion is configured such that a first periphery surface extends from the the first end surface to the location where the projection projects from the periphery (10c, 10d) of the optical coupling portion and a second periphery surface extends from the second end surface to the location where the projection projects from the periphery (10c, 10d) of the optical coupling portion, wherein the first and second periphery surfaces (10c, 10d) have different lengths in an optical-axis direction, and characterized in that the periphery surface that is shorter than the other periphery surface in the optical-axis direction is tapered to have an inclination angle greater than that of the other periphery surface that is longer in the optical-axis direction. a substantially cylindrical optical coupling portion whose opposite end surfaces (10a, 10b) respectively face the optical fiber and the optical element; and a projection projecting from a periphery (10c, 10d) of the optical coupling portion in a radial direction, the projection being located closer towards one of the opposite end surfaces (10a, 10b) with respect to a center position between the opposite end surfaces (10a, 10b), wherein a diameter of the optical coupling portion at a position corresponding to a first end surface of the projection is substantially equal to a diameter of the optical coupling portion at a position corresponding to a second end surface of the projection, and wherein the periphery (10c, 10d) of the optical coupling portion includes periphery surfaces (10c, 10d) that are tapered from the positions corresponding to the first and second end surfaces of the projection re-spectively towards the opposite end surfaces of the optical coupling portion and wherein the optical coupling portion is configured such that a first periphery surface extends from the the first end surface to the location where the projection projects from the periphery (10c, 10d) of the optical coupling portion and a second periphery surface extends from the second end surface to the location where the projection projects from the periphery (10c, 10d) of the optical coupling portion, wherein the first and second periphery surfaces (10c, 10d) have different lengths in an optical-axis direction, and characterized in that the periphery surface that is shorter than the other periphery surface in the optical-axis direction is tapered to have an inclination angle greater than that of the other periphery surface that is longer in the optical-axis direction.