A transmission comprising: a case; a first shaft which is housed in the case and rotatably supported by the case; a plurality of gears (10; 11; 12) which is housed in the case and rotatably provided relative to the first shaft; a movable element configured to rotate together with the first shaft in the case and to be movable in an axial direction of the first shaft, and selectively couples one of the gears (10; 11; 12) with the first shaft to be rotatable together; a second shaft which is movably supported by the case in an axial direction of the second shaft and rotatable around a shaft center (Ax) representing select positions of the transmission, wherein the second shaft is moved to two shift positions in the axial direction of the second shaft at each of the select positions; a shift fork which is swingably supported by the case and moves the movable element in the axial direction of the first shaft by swing of the shift fork in accordance with an axial motion of the second shaft to the two shift positions; two first protrusions which are provided on the second shaft and spaced apart from each other in the axial direction of the second shaft; and a second protrusion which is provided on the shift fork, the transmission being characterized in that the second protrusion, when the shift fork is selected by rotation of the second shaft being now in one of the select positions, is positioned between the two first protrusions and overlaps with the first protrusions viewed from the axial direction of the second shaft, wherein the shift fork swings by movement of the second shaft in the axial direction of the second shaft when the two first protrusions and the second protrusion overlap with each other viewed from the axial direction of the second shaft, wherein a protruding direction of the first protrusions and a protruding direction of the second protrusion are orthogonal to a swinging center of the shift fork when viewed in the axial direction of the second shaft, wherein the second protrusion protrudes from the shift fork toward the swinging center, an wherein the second shaft is positioned between the second protrusion and the swinging center viewed in the axial direction of the second shaft. a case; a first shaft which is housed in the case and rotatably supported by the case; a plurality of gears (10; 11; 12) which is housed in the case and rotatably provided relative to the first shaft; a movable element configured to rotate together with the first shaft in the case and to be movable in an axial direction of the first shaft, and selectively couples one of the gears (10; 11; 12) with the first shaft to be rotatable together; a second shaft which is movably supported by the case in an axial direction of the second shaft and rotatable around a shaft center (Ax) representing select positions of the transmission, wherein the second shaft is moved to two shift positions in the axial direction of the second shaft at each of the select positions; a shift fork which is swingably supported by the case and moves the movable element in the axial direction of the first shaft by swing of the shift fork in accordance with an axial motion of the second shaft to the two shift positions; two first protrusions which are provided on the second shaft and spaced apart from each other in the axial direction of the second shaft; and a second protrusion which is provided on the shift fork, the transmission being characterized in that the second protrusion, when the shift fork is selected by rotation of the second shaft being now in one of the select positions, is positioned between the two first protrusions and overlaps with the first protrusions viewed from the axial direction of the second shaft, wherein the shift fork swings by movement of the second shaft in the axial direction of the second shaft when the two first protrusions and the second protrusion overlap with each other viewed from the axial direction of the second shaft, wherein a protruding direction of the first protrusions and a protruding direction of the second protrusion are orthogonal to a swinging center of the shift fork when viewed in the axial direction of the second shaft, wherein the second protrusion protrudes from the shift fork toward the swinging center, an wherein the second shaft is positioned between the second protrusion and the swinging center viewed in the axial direction of the second shaft.