A tire for a motorcycle wherein the radius of curvature (R1) of a corner portion on one side (an inside in an axial direction) of a groove of the tire is smaller than a radius of curvature (R2) of the other corner portion; the radii of curvature (R1) and (R2) are set to be 2 mm or more; a first phantom circle for defining the corner portion is inscribed on a second phantom circle for defining the corner portion; the point of contact of the first phantom circle and the second phantom circle is positioned on the outside from the center of a groove; and the distance between the center of the groove and the point of contact is equal to or smaller than one fifth of the width (B) of the groove.