A bicycle crank axle comprises an axle body having first and second end portions, a plurality of first splines disposed at the first end portion of the axle body, a plurality of second splines disposed at the second end portion of the axle body, and a projection extending radially outwardly from the first end portion of the axle body, wherein the projection is structured to abut against a lateral outer surface of a bicycle crank arm to prevent the bicycle crank arm from moving axially outward. A separate projecting member is mounted to the first end of the axle body to form the projection. The plurality of first splines extend radially outwardly from an outer peripheral surface of the axle body for engaging a splined surface of the bicycle crank arm, but the plurality of second splines do not extend radially outwardly relative to the outer peripheral surface of the axle body.