An impact tool for removal and attachment of a mower blade cutting edge insert of the type demountably attached with a press fit wedging connection in a recessed end surface of the mower blade, the tool body having a U-shaped slot permitting the slot to receive and straddle adjacent edges of the mower blade and the insert when the latter is in the recessed end surface portion, sliding movement of the tool along the edges causes a contacting abutment in the bottom of the U-shaped slot to engage one or the other ends of the edge insert to drive the insert into or detach it from an operative press fit attachment.