An attachment for use with a saber saw which enables the saber saw to make straight non-wandering cuts. The attachment includes a plate which is secured flatwise to the base of the saber saw and a supporting fin extends downwardly from the plate and is located behind the reciprocating blade of the saber saw. The lower portion of the fin has a pair of spaced guides which define a slot to receive the blade. The fin and guide members maintain the blade in perpendicular relation to the base plate and prevent deformation of the blade as a cut is made.