A straddled electric vehicle comprising: a motor (32;32A;32B) comprising an electric motor; a driving wheel; and a power transmission mechanism (40;40A;40B) having a plurality of shafts for transmitting driving power from the motor to the driving wheel, the power transmission mechanism comprising: a first shaft (42;41A); a rotating member (44;43A) attached to the first shaft and being capable of exchanging a rotating force with the first shaft; and an elastic member (51;51A;51B) capable of biasing one of the rotating member attached to the first shaft and the first shaft toward an axial direction, characterised in that the first shaft (42;41A) has spline gears on a surface thereof, the spline gears being inclined relative to an axial direction of the first shaft and the rotating member has spline gears engageable with the spline gears on the first shaft, wherein the spline gears on the first shaft are inclined so as to move the rotating member or the first shaft toward the other axial direction when the driving wheel is rotating in a direction causing the straddled electric vehicle to advance and the rotating member or the first shaft acts to maintain a speed of rotation of the driving wheel as the speed of rotation is decreasing. a motor (32;32A;32B) comprising an electric motor; a driving wheel; and a power transmission mechanism (40;40A;40B) having a plurality of shafts for transmitting driving power from the motor to the driving wheel, the power transmission mechanism comprising: a first shaft (42;41A); a rotating member (44;43A) attached to the first shaft and being capable of exchanging a rotating force with the first shaft; and an elastic member (51;51A;51B) capable of biasing one of the rotating member attached to the first shaft and the first shaft toward an axial direction, characterised in that the first shaft (42;41A) has spline gears on a surface thereof, the spline gears being inclined relative to an axial direction of the first shaft and the rotating member has spline gears engageable with the spline gears on the first shaft, wherein the spline gears on the first shaft are inclined so as to move the rotating member or the first shaft toward the other axial direction when the driving wheel is rotating in a direction causing the straddled electric vehicle to advance and the rotating member or the first shaft acts to maintain a speed of rotation of the driving wheel as the speed of rotation is decreasing. a first shaft (42;41A); a rotating member (44;43A) attached to the first shaft and being capable of exchanging a rotating force with the first shaft; and an elastic member (51;51A;51B) capable of biasing one of the rotating member attached to the first shaft and the first shaft toward an axial direction, characterised in that the first shaft (42;41A) has spline gears on a surface thereof, the spline gears being inclined relative to an axial direction of the first shaft and the rotating member has spline gears engageable with the spline gears on the first shaft, wherein the spline gears on the first shaft are inclined so as to move the rotating member or the first shaft toward the other axial direction when the driving wheel is rotating in a direction causing the straddled electric vehicle to advance and the rotating member or the first shaft acts to maintain a speed of rotation of the driving wheel as the speed of rotation is decreasing.