A power transmission device includes first and second engaging elements, a power transmission, and first and second bearings. The first engaging element is rotatable with a first rotation shaft about a rotation axis. The second engaging element is rotatable with a second rotation shaft about the rotation axis. The power transmission is provided between the first engaging element and the second engaging element. The first bearing is provided between the rotation axis and the second engaging element in a radial direction with respect to the rotation axis and supports a first part of the second engaging element. The second engaging element is between the second bearing and the rotation axis in the radial direction. The second bearing supports a second part of the second engaging element. The second part is farther from the first engaging element in an axis direction than the first part.