To easily repair a runner blade at earth-sand abrasion caused time by installing a protecting liner in an earth-sand abrasion easily causing part of an outer periphery of a runner blade main body so as to be mountable/ demountable.

When the earth-sand abrasion quantity of a protecting liner 72 installed by plural bolts from the upstream side by covering the outer periphery of a runner blade main body 71 exceeds a limit, only the protecting liner 72 is welded/repaired by padding or can be replaced with a new article by removing the protecting liner 72 from the runner blade main body 71 by loosening the bolts. Therefore, a runner blade 7 at earth-sand abrasion caused time can be easily repaired. A construction material of the protecting liner 72 may be the same as the runner blade main body 71, but earth-sand abrasion can be reduced further by using a material having higher hardness.