Abstract: A mortising machine having a mortising tool which is designed to oscillate on an elliptical path; the mortising tool is supported on a carrier shaft which is eccentric to a motor drive shaft; the invention concerns the eccentric support for the support shaft and the elements that attach the mortising tools to the carrier shaft, in particular a sleeve is supported on its exterior and is rotated concentrically with the motor shaft, the sleeve has an eccentric opening which rotatably receives another sleeve also having an eccentric opening in it and the carrier shaft is carried in the latter opening.