A motorcycle wheel speed sensor mounting structure, includes an axle holder for supporting a front wheel is disposed below a front fork of the motorcycle and an axle support disposed in a lower part of the axle holder. Further, a caliper mount, for supporting a brake caliper of a disc brake, is disposed on a rear portion of the axle holder and a wheel speed sensor is mounted on the caliper mount, wherein the wheel speed sensor is located above a line connecting a lower end of the axle support to a lower end of the caliper mount.