A power transmission mechanism comprising: a first shaft including a first double-helical gear; a second shaft including a second double-helical gear and a third double-helical gear, the second double-helical gear configured to mesh with the first double-helical gear, the third double-helical gear being arranged adjacent to the second double-helical gear in a direction of the second shaft; a third shaft including a fourth double-helical gear configured to mesh with the third double-helical gear; a first bearing being a rolling bearing rotatably supporting the first shaft; a second bearing being a rolling bearing rotatably supporting the second shaft; and a third bearing being a rolling bearing rotatably supporting the third shaft, the first double-helical gear and the first shaft being configured to integrally rotate, and integrally move in an axial direction, the second double-helical gear, the third double-helical gear, and the second shaft being configured to integrally rotate, and integrally move in the axial direction, the fourth double-helical gear and the third shaft being configured to integrally rotate, and integrally move in the axial direction, and characterized in that the second bearing being configured such that at least one of conditions i) and ii) is satisfied: i) an amount of axial displacement of the second bearing relative to a force in the axial direction generated at a meshing part between the first double-helical gear and the second double-helical gear is smaller than an amount of axial displacement of the first bearing relative to the force in the axial direction generated at the meshing part between the first double-helical gear and the second double-helical gear, and ii) an amount of axial displacement of the second bearing relative to a force in the axial direction generated at a meshing part between the third double-helical gear and the fourth double-helical gear is smaller than an amount of axial displacement relative of the third bearing relative to the force in the axial direction generated at the meshing part between the third double-helical gear and the fourth double-helical gear. a first shaft including a first double-helical gear; a second shaft including a second double-helical gear and a third double-helical gear, the second double-helical gear configured to mesh with the first double-helical gear, the third double-helical gear being arranged adjacent to the second double-helical gear in a direction of the second shaft; a third shaft including a fourth double-helical gear configured to mesh with the third double-helical gear; a first bearing being a rolling bearing rotatably supporting the first shaft; a second bearing being a rolling bearing rotatably supporting the second shaft; and a third bearing being a rolling bearing rotatably supporting the third shaft, the first double-helical gear and the first shaft being configured to integrally rotate, and integrally move in an axial direction, the second double-helical gear, the third double-helical gear, and the second shaft being configured to integrally rotate, and integrally move in the axial direction, the fourth double-helical gear and the third shaft being configured to integrally rotate, and integrally move in the axial direction, and characterized in that the second bearing being configured such that at least one of conditions i) and ii) is satisfied: i) an amount of axial displacement of the second bearing relative to a force in the axial direction generated at a meshing part between the first double-helical gear and the second double-helical gear is smaller than an amount of axial displacement of the first bearing relative to the force in the axial direction generated at the meshing part between the first double-helical gear and the second double-helical gear, and ii) an amount of axial displacement of the second bearing relative to a force in the axial direction generated at a meshing part between the third double-helical gear and the fourth double-helical gear is smaller than an amount of axial displacement relative of the third bearing relative to the force in the axial direction generated at the meshing part between the third double-helical gear and the fourth double-helical gear. i) an amount of axial displacement of the second bearing relative to a force in the axial direction generated at a meshing part between the first double-helical gear and the second double-helical gear is smaller than an amount of axial displacement of the first bearing relative to the force in the axial direction generated at the meshing part between the first double-helical gear and the second double-helical gear, and ii) an amount of axial displacement of the second bearing relative to a force in the axial direction generated at a meshing part between the third double-helical gear and the fourth double-helical gear is smaller than an amount of axial displacement relative of the third bearing relative to the force in the axial direction generated at the meshing part between the third double-helical gear and the fourth double-helical gear.